WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry

Organic Chemistry Topic A General Properties Of Organic Compounds Synopsis:

1. In 1828, a German chemist Friedrich Wohler synthetically prepared urea, an organic compound found in the urine of most mammals, by heating an inorganic compound, ammonium .cyanate. This accidental synthesis gave a fatal blow to the ‘vital force theory’ in which it was considered impossible to prepare an organic compound in the laboratory from inorganic compounds.

2. The fundamental element of all organic compounds is carbon. Apart from carbon, H, O, N, S, P, halogens and some metals may also be present in organic compounds.
3. The self-linking property of carbon by virtue of which its atoms mutually combine with each other to form long open chains (straight or branched) and rings is called catenation. Using its catenation property, carbon forms a vast number of organic compounds.
4. Organic compounds in which all the adjacent carbon atoms are linked to one another by single bonds only are called saturated compounds. For example, methane, ethane.

Read and Learn Also WBBSE Solutions for Class 10 Physical Science and Environment

5. Organic compounds which contain at least one carbon-carbon double bond or triple bond are called unsaturated compounds. For example, ethylene, and acetylene.
6. Organic compounds containing carbon and hydrogen are called hydrocarbons.
7. An atom or a group of atoms present in an organic compound, which determines the nature and characteristic chemical properties of the compound is called a functional group.

8. The phenomenon of existence of two or more compounds possessing the same molecular formula but different physical and chemical properties is called isomerism. Such compounds showing isomersim are called isomers.
9. The compounds having the same molecular formula but different structures are called structural isomers and the phenomenon is known as structural isomerism.

10. Structural isomerism may arise due to differences in functional groups or positions of the functional groups in the carbon chain.

ch3ch2ch2oh Iupac Name

Example of functional group isomerism:

CH3 — O — CH3 (dimethyl ether)
CH3 CH2 — OH (ethanol)

Example of positional isomerism:

CH3CH2CH2OH (propan-1-ol)
CH3 — CH(OH) — CH3 (propan-2-ol)

11. A homologous series may be defined as a series or group of similarly constituted organic compounds having same functional group and same general formula arranged in increasing order of molecular mass. Any two successive members of a homologous series differ in their molecular formula by ‘a’ CH2 group or unit. The members of a homologous series are called homologues.

ch3ch2ch2oh Iupac Name

12. General formula of the homologous series of alkanes is CnH2n + 2 and the general formulae of alkene and alkyne are CnH2n-2 and CnH2n respectively.
13. A scientific and systematic approach of naming the organic compounds was adopted in a conference attended by chemists from worldwide. These rules of naming organic compounds are collectively known as IUPAC (International Union of Pure and Applied Chemistry) nomenclature of organic compounds. These rules have been modified from time to time.

Organic Chemistry Topic A General Properties Of Organic Compounds Short And Long Answer Type Questions:


Question 1. Write three differences between organic and inorganic compounds.

Answer:

The major differences between organic and inorganic compounds are as follows:

Property Organic compound Inorganic compound
1. Constituents All organic compounds must contain carbon. Apart from carbon, elements like H, N, 0, S, P, halogens etc., may also be present in organic compounds. Existence of more than 20 lakhs of organic compounds is known till date. Inorganic compounds may or may not contain carbon. About 92 naturally occurring elements and some synthetically prepared elements form almost 90000 inorganic compounds which is far less than the number of organic compounds.
2. Melting point and boiling point Organic compounds being covalent in nature generally have low melting and boiling points. Most inorganic compounds being ionic in nature have high melting and boiling points.
3. Solubility Organic compounds are soluble in organic and non-polar solvents like benzene, CCI4 etc., but insoluble in polar solvents such as water. Inorganic compounds are generally soluble in polar solvents such as water but insoluble in non-polar solvents such as benzene.

Question 2. The general molecular formula isomers is C4H8. Predict the structural formula of those compounds.

Answer: The general molecular formula of the isomers is C4H8. The formula conforms to the general formula CnH2n (where n = 4) which belongs to the alkene family. Therefore, the possible isomers and their structural formulas are as follows:

Wbbse Class 10 Physical Science Solutions

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Straight Chain And Branced Chain Isomers

 

 

Question 3. What is homologous series? Discuss the significance of homologous series.

Answer:

Homologous series

1. A homologous series may be defined as a series or a group of similarly constituted organic compounds having the same functional group and general formula arranged in order of their increasing molecular mass. Any two successive members of a homologous series differ in their molecular formula by a CH2 -group or unit. The members of a homologous series are called homologues.

2. If the method of preparation and properties of a certain member of a homologous series are known, then the method of preparation and properties of the other members of the same series can be easily predicted.

Wbbse Class 10 Physical Science Solutions

Question 4. Mention the important characteristics of a homologous series.

Answer:

The important characteristics of a homologous series

1. All the members of a homologous series have the same constituent elements and they can be represented by a single general formula.
2. If all the members of a homologous series are arranged in increasing order of their molecular masses, then two consecutive members of the family differ from one-another by one CH2 -group and the difference in their molecular mass is 14 units.
3. All the members of a homologous series have almost similar chemical properties.

Question 5. How was Berzelius’ ‘vital force theory’ proved invalid?

Answer: In 1828, scientist Wohler accidentally prepared urea, an organic compound, by heating an inorganic compound, ammonium cyanate. Later, in 1845, Kolbe and in 1856, Berthelot prepared acetic acid and methane respectively from their constituent elements in the laboratory.

All these discoveries proved that no vital force inherent to living beings was involved in the formation of organic compounds. Thus, the ‘vital force theory’ was proved invalid.

Wbbse Class 10 Physical Science Solutions

Question 6. Why are organic compounds generally insoluble in water (a polar solvent)?

Answer: As organic compounds are formed by covalent bonds, they do not dissociate or ionise in water or any other polar solvents. Consequently, no electrostatic force of attraction develops between the water molecules and the molecules of the organic compound.

So, organic compounds are insoluble in water. However, some organic compounds dissolve in water by forming hydrogen bonds with water molecules (such as alcohols, glucose etc.) or by ionising in water (such as carboxylic acids).

Question 7. Why are the solutions of organic compounds generally non-conductor of electricity?

Answer: As organic compounds are formed by covalent bonds, they do not ionise in water or any other polar solvents. Hence, they cannot conduct electricity in solutions. However, aqueous solutions of carboxylic acids such as formic acid, acetic acid etc., ionise in water and conduct electricity to a small extent.

Question 8. What is the catenation property of carbon?

Answer:

The catenation property of carbon

The unique self-linking property of carbon due to which C-atoms mutually combine with each other by forming covalent single, double or triple bonds to form long open chains (straight or branched) and rings of different sizes is called catenation property of carbon. Due to this reason, carbon forms a vast number of organic compounds.

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Catention Property Of Carbon

 

Question 9. Why is carbon able to show catenation property?

Answer: Due to the small size and moderate electronegativity of carbon atoms, it can form very strong and stable carbon-carbon covalent bonds. As a result, carbon atoms can link with one another by forming covalent single, double or triple bonds. For these reasons, carbon is able to show catenation property which leads to the formation of a large number of open chain and cyclic compounds.

Wbbse Class 10 Physical Science Solutions

Question 10. Briefly describe the tetrahedral model of the four valencies (bonds) of carbon as proposed by scientists van’t Hoff and Le Bel.

Answer: In 1874, scientists van’t Hoff and Le Bel proposed the tetrahedral model of the four valencies of carbon. According to this model—

1. All four valencies of a carbon atom cannot be on the same plane.
2. If a carbon atom is placed at the centre of an imaginary regular tetrahedron, then the four valencies of the C-atom will be directed towards the four corners of the tetrahedron.
3. The angle between any two valencies of the carbon atom is 109°28′.

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Tetrahedral Model Of Carbon

 

Question 11. Describe the structure of ethane (C2H6) with the help of a suitable diagram.

Answer:

The structure of ethane (C2H6) with the help of a suitable diagram

In ethane (C2H6), the two adjacent C-atoms equally share one electron pair among themselves to form a single bond. Each of the C- atoms then satisfies its remaining three valencies by forming three single bonds with three hydrogen atoms.

Wbbse Class 10 Physical Science Solutions

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Ethane Molecule

 

Question 12. Describe the structure of ethylene (C2H4) with the help of a suitable diagram.

Answer:

The structure of ethylene (C2H4) with the help of a suitable diagram

In ethylene (C2H4), the two adjacent C-atoms share two electron pairs with each other to form a double bond and satisfy two of its valencies. Each of the two C-atoms then fulfils its remaining two valencies by forming single bond with two hydrogen atoms each. All the atoms in the molecule remain on the same plane.

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Ethylene Molecule

 

Question 13. Describe the structure of acetylene (C2H2) with the help of a suitable diagram.

Answer:

The structure of acetylene (C2H2) with the help of a suitable diagram

In acetylene (C2H2), the two adjacent C-atoms share three electron pairs with each other to form a triple bond and satisfy three of its valencies. Each of the two C-atoms then fulfils its remaining valency by forming a single bond with one hydrogen atom each. All the atoms in the molecule remain in the same line and so, the molecule is linear in shape.

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Acetylene Molecule

 

Question 14. What do you mean by functional group? Give one example.

Answer:

Functional group

An atom or a group of atoms present in an organic compound which determines the nature and characteristic chemical properties of the compound is called a functional group.

Example: —OH is the functional group of the alcohol series.

Question 15. Write the name and structure of the functional group of the alcohol series. Give an example of a compound containing that functional group.

Answer: The functional group of the alcohol series is the hydroxyl group and its structure is given by

2. A compound containing —OH as the functional group is ethyl alcohol (C2H5OH).

Question 16. Write the name and structure of the functional group present in aldehydes. Give an example of a compound containing that functional group.

Answer: The functional group present in aldehydes is the formyl or aldehydic group and its structure is given by:

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Aldehydic Group And Its Structure

 

A compound containing — CHO as the functional group is acetaldehyde (CH3CHO).

Question 17. Write the name and structure of the functional group present in ketones. Give an example of a compound containing that functional group.

Answer: The functional group present in ketones is keto group and its structure is given by: WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Keto Group

A compound containing  WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Acetone Functional Group   as the functional group is acetone (CH3COCH3)

Question 18. Write the name and structure of the functional group present in carboxylic acids. Give an example of a compound containing that functional group.

Answer: The functional group present in carboxylic acids is the carboxyl group and its structure is given by:

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Carboxylic Acid

 

A compound containing — COOH as the functional group is acetic acid (CH3COOH).

Question 19. Write the name and structure of the functional group present in amines. Give an example of a compound containing that functional group.

Answer: The functional group present in amines is the amino group and its structure is given by:

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Amino Group And Its Structre

 

A compound containing -NH2 as the functional group is methylamine (CH3NH2)

Question 20. Write the name and structure of the functional group present in ethers. Give an example of a compound containing that functional group.

Answer: The functional group present in ethers is the ether group and its structure is given by: WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry

A compound containing — O — as the functional group is dimethyl ether (CH3OCH3).

Question 21. What is functional group isomerism? Give example.

Answer:

Functional group isomerism

The phenomenon of the existence of two or more compounds having the same molecular formula but different functional groups (i.e., belonging to different families) is called functional group isomerism.

Example: The functional groups in dimethyl ether (CH3 — O — CH3) and ethyl alcohol ( C2H5OH) are — O — and — OH respectively but both of these compounds have the same molecular formula of C2H6O.

Question 22. What is positional isomerism? Give example.

Answer:

Positional isomerism

The phenomenon of the existence of two or more compounds having the same structure of the carbon chain, i.e., the same carbon skeleton, but differing in the position of the multiple bond or functional group is called positional isomerism.

Example: The compounds, propan-1-ol or n- propyl alcohol (CH3CH2CH2OH) and propan-2-ol or isopropyl alcohol [CH3CH(OH)CH3] both have the same molecular formula C3H8O, but the positions of — OH group is different in both the compounds.

Question 23. The members of a homologous series generally show similar chemical properties but different physical properties. Why?

Answer:

The members of a homologous series generally show similar chemical properties but different physical properties.

Due to the presence of the same functional group, the members of a particular homologous series show similar chemical properties. However, as the molecular masses of the members of a homologous series are different, the physical properties (such as melting point, boiling point, density etc.) dependent on the molecular mass of a compound are also different for the homologues.

Question 24. Only one alkyl group is formed from ethane whereas two different alkyl groups are formed from propane. Why?

Answer:

Only one alkyl group is formed from ethane whereas two different alkyl groups are formed from propane.

All the 6 H-atoms in an ethane molecule are equivalent. Hence, the removal of any one hydrogen atom from ethane produces the same alkyl group, i.e., the ethyl group ( — CH2CH3). On the other hand, two different types of hydrogen atoms are present in propane.

The two hydrogen atoms bonded to the central C-atom are different from the 6 H-atoms bonded to the terminal C-atoms in propane. So, the removal of the terminal H-atom produces an n-propyl group (CH3CH2CH2—) whereas the removal of the non-terminal H-atom produces an isopropyl group WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry


Question 25. Give the IUPAC names and structural formulas of the alkynes containing up to C-atoms.

Answer: HC = CH : ethyne
H3C — C Ξ CH : propyne

Question 26. Give the IUPAC names and structural formulas of the alcohols containing up to 3 C-atoms.

Answer:

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry IUPAC Names And Structural Formulas Of The Alochols

 

Question 27. Give the IUPAC names and structural formulas of the carbonyl compounds containing upto 3 C-atoms.

Answer:
Aldehydes:
HCHO: methanal
CH3CHO : ethanal
CH3CH2CH3CHO: propanal

Ketones:
CH3COCH3: propanone

Question 28. Give the IUPAC names and structural formulas of the carboxylic acids containing upto 3 C-atoms.

Answer:
HCOOH: methanoic acid
CH3COOH: ethanoic acid
CH3CH2COOH : propanoic acid

Question 29. (1) Who proved that the main component of all organic compounds is carbon?
(2)All organic compounds contain carbon but all carbon compounds are not organic compounds. Explain

Answer:
(1) Scientist Lavoisier proved that the main component of all organic compounds is carbon.
(2) All carbon compounds are not organic compounds. Compounds like carbon monoxide, carbon dioxide, metallic carbonate, metallic bicarbonate, metallic cyanite etc. can not be termed as organic compounds as catenation property of carbon, isomerism etc. are not seen in these compounds. They all are inorganic compounds.

Question 30. What is a saturated compound? Give examples.

Answer:

Saturated compound

Organic compounds, in which all of the carbon atoms are attached through covalent single bonds are called saturated compounds.

Examples of saturated compounds are—

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Saturated Compounds

 

Question 31. What is an unsaturated compound? Give examples.

Answer:

Unsaturated compound

Organic compounds, in which at least two carbon atoms are attached through covalent double or triple bonds, are called unsaturated compounds.

Examples of unsaturated compounds are—

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Unsaturated Compounds

 

Question 32. What are alkenes or olefines? Give examples.

Answer:

Alkenes or olefines

Unsaturated hydrocarbons which contain at least one carbon-carbon double bond are called alkenes or olefins. The general formula of alkenes are
CnH2n.

Examples: ethylene (CH2=CH2), propene (CH3 — CH = CH2) etc.

Question 33. What are alkynes? Give examples.

Answer:

Alkynes

Unsaturated hydrocarbons which contain at least one carbon-carbon triple bond are called alkynes.

Examples: H — C Ξ C — H(acetylene),  CH3 — C=C-H(propyne)

Question 34. Differentiate between saturated and unsaturated hydrocarbons.

Answer:

Differences between saturated and unsaturated hydrocarbons are—

Topic Saturated hydrocarbon Unsaturated hydrocarbon
1. Nature of bond Carbon atoms are attached through a covalent single bond. At least two carbon atoms are attached through the double or triple bond.
2. Reactivity Reactivity is comparatively less. Chemical reactivity is comparatively more.
B. Nature of reaction Usually participates in substitution reactions. Usually participates in addition reactions.
4. Reaction with Br2 water No reaction takes place. The red colour of bromine water remains unaltered. An additional reaction takes place. The red colour of bromine water turns colourless.

 

Question 35. Why is C2H6 termed as saturated hydrocarbon but C2H4 is termed as unsaturated hydrocarbon?

Answer: All the carbon atoms of C2H6 are attached through the covalent single bond, hence it is termed as saturated hydrocarbon.

On the other hand, in C2H4, two adjacent carbon atoms are attached through a covalent double bond and hence it is termed as an unsaturated hydrocarbon.

Question 36. What do you mean by isomerism and isomer?

Answer:

Isomerism and isomer

1. The phenomenon of the existence of two or more compounds possessing the same molecular formula but different physical and chemical properties is known as isomerism.
2. Compounds with the same molecular formula but different physical and chemical properties, are termed as isomers to each other.

Question 37. Write down the definition and example of structural isomerism.

Answer: The phenomenon of existence of two or more compounds having the same molecular formula but different structures are called structural isomerism. For example, two structural isomers having the molecular formula C2H6O are—

H3C — CH2 — OH (ethanol) and H3C — O —CH3 (dimethyl ether)

Question 38. How would you identify two isomeric compounds denoted by the formula C2H6O? Or, Distinguish between ethanol and dimethyl ether by a chemical reaction.

Answer: Two compounds having same formula of C2H6O are dimethyl ether and ethanol. Ethanol reacts with sodium metal at room temperature, forming sodium ethoxide and H2 gas. But dimethyl ether does not react with sodium.

2CH3CH2OH + 2Na → 2CH3CH2ONa + H2
CH3 – O – CH3 + Na → no reaction

Question 39. Write down the structural formula and IUPAC name of the following compounds:
1.CH3CH2CH3
2. CH2= CH2
3.  H3C-CH=CH2
4. CH=CH
5.  CH3-CH,CH
6. CH3CH2OH
7. CH3CH(OH)CH3
8. CH3CH2CH2OH
9. CH2(OH)CH(OH)CH2(OH)
10. (CH3)3COH
11. C(CH3)3CHO
12. (CH3)2C= CH2
13. CH3COCH3
14. CH2(CI)CH2(Cl)
15. CH3CH(CI)CH3

Answer:

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry IUPAC Names And Structural Formulas Of The Alcohols

Question 40. Write down the structural formula of—  

1. Ethanal
2. Methanoic acid
3. 2 -methyl propanal
4. 2,2-dichloro propane
5. Ethanoic acid
6. Ethanoic-1, 2-dioic acid
7. Tricloromethane
8. Methanol
9. Acetone

Answer:
WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Structural Formulas

 

Organic Chemistry Topic A General Properties Of Organic Compounds Answer In Brief:

 

Question 1. Give the chemical equation for the reaction by which urea is produced from ammonium cyanate.
Answer: The chemical equation for the reaction by which urea is produced from ammonium cyanate is—

⇒ \(\underset{\text { (Ammonium cyanate) }}{\mathrm{NH}_4 \mathrm{CNO}} \frac{\text { heat }}{\text { (rearrangement) }} {\mathrm{NH}_2 \mathrm{CONH}_2}\)

Question 2. Give some examples of organic solvents.
Answer: Some examples of organic solvents are benzene, chloroform, acetone, ethanol etc.

Question 3. What are hydrocarbons?
Answer: The binary compounds of carbon and hydrogen are called hydrocarbons.

Question 4. What are saturated hydrocarbons?
Answer: The hydrocarbons in which all the C-atoms are linked to one another through single covalent bonds only are called saturated hydrocarbons. For example, methane, ethane, and propane.

Question 5. What are unsaturated hydrocarbons?
Answer: The hydrocarbons containing at least a double or a triple bond are called unsaturated hydrocarbons. For example, ethylene, and acetylene.

Question 6. Why are alkanes also known as paraffin?
Answer: Alkanes are also known as paraffin due to their less reactive nature.

Question 7. To which class do the organic compounds containing —the CHO group belong?
Answer: The organic compounds containing CHO as the functional group belongs to aldehyde.

Question 8. To which class do the organic compounds containing —CO— as the functional group belongs?
Answer: The organic compounds containing —CO — as the functional group belongs to the ketone.

Question 9. To which class do the organic compounds containing —COOH as the functional group belongs?
Answer: The organic compounds containing — COOH as the functional group belong to carboxylic acid.

Question 10. To which class do the organic compounds containing —NH2 as the functional group belongs?
Answer: The organic compounds containing —NH2 as the functional group belongs to an amine.

Question 11. To which class do the organic compounds containing — O— as the functional group belongs?
Answer: The group name for organic compounds containing —O— as the functional group is ether.

Question 12. Name the first member of the alcohol homologous series. What is its IUPAC name?
Answer: The first member of the alcohol homologous series is methyl alcohol (CH3OH).
Its IUPAC name is methanol.

Question 13. Name the first member of the aldehyde homologous series. What is its IUPAC name?
Answer: The first member of the aldehyde homologous series is formaldehyde (HCHO).
Its IUPAC name is methanal.

Question 14. Name the first member of the ketone homologous series. What is its IUPAC name?
Answer: The first member of the ketone homologous series is acetone (CH3COCH3).
Its IUPAC name is propanone.

Question 15. Name the first member of the carboxylic acid homologous series. What is its IUPAC name?
Answer: The first member of the carboxylic acid homologous series is formic acid (HCOOH).
Its IUPAC name is methanoic acid.

Question 16. Name the first member of the amine homologous series. What is its IUPAC name?
Answer: The first member of the amine homologous series is methylamine (CH3NH2).
Its IUPAC name is methenamine.

Question 17. Name the first member of the ether homologous series. What is its IUPAC name?
Answer: The first member of the ether homologous series is dimethyl ether(CH3OCH3).
Its IUPAC name is methoxymethane.

Question 18. What is isomerism?
Answer: The phenomenon of the existence of two or more compounds having the same molecular formula but different chemical and physical properties is called isomerism.

Question 19. What do you mean by structural isomerism?
Answer: The phenomenon of the existence of two or more compounds having the same molecular formula but different physical and chemical properties due to differences in their structures i.e., different bonding sequences is called structural isomerism.

Question 20. Between ethyl alcohol and dimethyl ether, which one does not react with metallic sodium?
Answer: Between ethyl alcohol and dimethyl ether, the latter does not react with metallic sodium.

Question 21. What is the minimum number of C-atoms required to represent the structural formula of a ketone?
Answer: A minimum of three C-atoms are required to represent the structural formula of a ketone.

Question 22. Name the two scientists who proved ‘the vital force theory’ wrong successfully synthesising acetic acid and methane in the laboratory.
Answer: Kolbe and Berthelot were the scientists who proved ‘the vital force theory’ to be wrong.

Question 23. Which two alkyl groups are formed when one hydrogen atom is removed from propane?
Answer: The two alkyl groups formed are—the propyl group (CH3CH2CH2 —) and the isopropyl group
(H3C — CH — CH3).

Question 24. Why is ethanol called ‘grain alcohol’?
Answer: Ethanol is also called ‘grain alcohol’ because it can be prepared by the fermentation of finely ground grains (such as corn).

Question 25. Which type of chemical bond is present in organic compounds?
Answer: Covalent bond.

Question 26. Give an example of a biomolecule.
Answer: Glucose.

Question 27. State whether the organic compound of molecular formula C4H8 is saturated or unsaturated?
Answer: C4H8 (CnH2n, where n = 4) is an alkene compound, hence it is unsaturated in nature.

Question 28. Write down the number of H-atoms present in 4C-alkane.
Answer: The number of H-atoms in a 4C-alkane is 10.

Question 29. What is the number of H-atoms in a 3- carbon alkyne?
Answer: The number of ‘H’-atoms in a 3-carbon alkyne is 4.

Question 30. Name the simplest alkyne.
Answer: Ethyne (H — C = C — H).

Question 31. Which type of hydrocarbon is acetylene?
Answer: Acetylene is an unsaturated hydrocarbon.

Question 32. What is the H — C—H bond angle in methane molecules?
Answer: 109°28′

Question 33. How many chemical bonds are there in ethylene?
Answer: 6 chemical bonds are present in ethylene.

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry 6 Chemical Bonds Present In Ethylene

Question 34. Write down the H —C —H bond angle in ethylene.
Answer: The h — C—H bond angle in ethylene is 120°

Question 35. Give an example of a non-carbon functional group.
Answer: Hydroxyl ( — OH).

Question 36. Which type of isomerism can be seen in propanone and propanal?
Answer: Functional group isomerism.

Question 37. Write down the formula of functional group isomer of CH3CH2OH.
Answer: CH3 — O — CH3 (dimethyl ether)

Question 38. Write down the structural formula of positional isomer of CH3CH2CH2OH.
Answer: Equation

Question 39. Write down the next two higher homologue of methane.
Answer: C2H6 (ethane) and C3H (propane).

Question 40. Write down the formula of first alkene homologue.
Answre: CH2 = CH2 (ethene)

Question 41. Write down the next homologue of C2H5OH.
Answer: The next homologue of C2H5OH is propanol (C3H7OH).

Question 42. Write down the full form of IUPAC.
Answer: International Union of Pure and Applied Chemistry.

Question 43. Write down the formula of prop-1-ene.
Answer: Formula of prop-1-ene is H2C = CH — CH3.

Question 44. Write down the IUPAC name of HC = CH.
Answer: IUPAC name of HC ≡ CH is ethyne.

Question 45. Write down the IUPAC name of CH3CH2OH.
Answer: ethanol.

Question 46. Write down the IUPAC name of CH3CH2CH2OH.
Answer: propan-1-ol.

Question 47. Write down the IUPAC name of CH3CH2CHO.
Answer: propanal.

Question 48. Write down the IUPAC name of CH3CH2COOH.
Answer: propanoic acid.

 

Organic Chemistry Topic A General Properties Of Organic Compounds Fill In The Blanks:

 

Question 1. Organic compounds are generally insoluble in ______ solvents.
Answer: Polar

Question 2. Most organic compounds are combustible due to the presence of _____ and _______.
Answer: Carbon, hydrogen

Question 3. Organic compounds do not ______ when dissolved in suitable solvents.
Answer: Ionise

Question 4. A carbon atom forms _______ bond with other atoms.
Answer: Covalent

Question 5. In most cases/carbon cannot form _____ compounds.
Answer: Ionic

Question 6. In the tetrahedral model of C-atom, all the four bonds of carbon atom does not remain on the ______ plane.
Answer: Same

Question 7. In the tetrahedral arrangement of four valencies of carbon, the carbon atom is present at the ______ of the tetrahedron and the four bonds are directed towards the four ______ of the tetrahedron.
Answer: Center, Corners

Question 8. The large number of organic compounds exists due to _____ and______ Of carbon.
Answer: Catenation, Isomerism

Question 9. The chain formed by carbon atoms due to catenation may be either ______ or ______
Answer: Open, Cyclic

Question 10. In methane, all the four valencies of carbon atom are satisfied by ______
Answer: Single, Bonds

Question 11. The ______ of an organic compound determines its chemical property.
Answer: Functional group

Question 12. The chemical reactivity of saturated hydrocarbons is very _____ while that of unsaturated hydrocarbons is quite ______
Answer: Less, high

Question 13. Between alcohols and ethers, _______ are relatively less reactive.
Answer: Ethers

Question 14. Between aldehydes and ketones, ______ are chemically more reactive.
Answer: Aldehyde

Question 15. If an alcohol and an ether are isomers, then it is an example of ______ isomerism.
Answer: Functional group

Question 16. Two adjacent members of a homologous series differ in their molecular formula by a _____ group.
Answer: CH2

Question 17. All the compounds of a homologous series contain the same _____
Answer: Functional group

Question 18. The chemical properties of all the members of a homologous series is generally_________
Answer: Identical

Question 19. The phenomenon of similarity in the properties of the members of a homologous series is known as ________
Answer: Homology

Question 20. When one hydrogen atom is removed from ethane, _______ group is formed.
Answer: ethyl

Question 21. The IUPAC name of the carboxylic acid having lowest molecular mass is _______
Answer: Methanoic acid

Question 22. The IUPAC name of the aldehyde containing two C-atoms is ______
Answer: Ethanal

Question 23. Covalent compounds are usually _________ in water.
Answer: Insoluble

Question 24.Different compounds with same molecular formula are ______ to each other.
Answer: Isomers

Question 25. n -propyl alcohol and isopropyl alcohol are _______ isomers.
Answer: Positional

 

Organic Chemistry Topic A General Properties Of Organic Compounds State Whether True Or False:

 

Question 1. The first organic compound to be synthesised from an inorganic compound is acetic acid.
Answer False

Question 2. Methane and ethane are saturated hydrocarbons while ethylene and acetylene are unsaturated hydrocarbons.
Answer: True

Question 3. In C2H2, the two adjacent carbon atoms are linked by a double bond.
Answer: False

Question 4. Alkenes are also called olefins because the lower members of this family react with halogens to form oily substances.
Answer: True

Question 5. Ethylene reacts with sulphur monochloride ( S2CI2) to produce mustard gas.
Answer: True

Question 6. CnH2n+1OH is the general formula of carboxylic acids.
Answer: False

Question 7. 2-bromopentane and 3-bromopentane are positional isomers.
Answer: True

Question 8. The molecular formula, C3H6O, represents two functional isomers namely, acetone and propionaldehyde.
Answer: True

Question 9. Thermal decomposition of organic compounds is known as pyrolysis.
Answer: True

Question 10. The first member of the aldehyde family is formaldehyde and its IUPAC name is ethanal.
Answer: False

Question 11. The IUPAC name of dimethyl ether is methoxymethane.
Answer: True

Question 12. Aldehydes and ketones are collectively known as carbonyl compounds.
Answer: True

Question 13. Ethane can decolourise the red colour of Br2 dissolved in carbon tetrachloride solution.
Answer: True

Question 14. If one hydrogen atom is removed from propane, then two alkyl groups are formed namely, propyl and isopropyl.
Answer: True

Question 15. All the organic compounds are made of carbon.
Answer: True

Question 16. Catenation is the property of organic compounds.
Answer: False

Question 17. Formula of the 3-carbon alkane is C3H6.
Answer: False

Question 18. H —C —H bond angle in methane is 120°.
Answer: False

Question 19. C2H6 is a saturated hydrocarbon.
Answer: True

Question 20. Number of H-atoms in a 2-carbon alkane is 5.
Answer: False

Question 21. Functional group of alcohol is —OH .
Answer: True

Question 22. Common name of methanal is formaldehyde.
Answer: True

Question 23. IUPAC name of formic acid is methanoic acid.
Answer: True

 

Organic Chemistry Topic B Methane, Ethylene, Acetylene, LPG And CNG Synopsis:

 

1. Methane (CH4), ethylene (C2H4) and acetylene (C2H2) are the first members of alkane, alkene and alkyne homologous series respectively. These compounds have extensive applications in different industries.
2. The gaseous component obtained at the time of refining crude petroleum by fractional distillation is liquefied under high pressure and stored in steel cylinders. This is known as LPG (Liquefied Petroleum Gas). It is widely used as a fuel.

3. The gas trapped in petroleum mines or coal mines is called natural gas. It is liquefied under high pressure and is known as CNG (Compressed Natural Gas). It is also used as a fuel. The main component of CNG is methane (~ 90%). Ethane, ethene, propane, butane and little amount of pentane is generally present in CNG, in addition to methane.

4. Methane is a saturated hydrocarbon belonging to the alkane family. It mainly participates in substitution reactions.

5. Combustion of methane: in presence of air, methane burns in a blue flame to form carbon dioxide and water.

⇒ \(\begin{array}{r}
\mathrm{CH}_4+2 \mathrm{O}_2 \rightarrow \mathrm{CO}_2+2 \mathrm{H}_2 \mathrm{O}+\text { heat } \\
(213 \mathrm{kcal} / \mathrm{mol})
\end{array}\)

6. Ethylene is an unsaturated hydrocarbon belonging to the alkene family. It mainly participates in addition reactions. Polythene, a polymer of ethylene, has many practical applications.

7. Addition reaction of ethylene: When ethylene gas is passed through Br2-solution (in CCI4,CHCI2), the red colour of the solution disappears and ethylene dibromide is formed.

8. Acetylene is an unsaturated hydrocarbon of the alkyne family and generally participates in addition reactions.

9. Uses of acetylene:
(1)Used to form oxyacetylene flame (3000°C)
(2)Used to form artificial rubber, artificial fibre, to lit carbide lamp, to form PVC etc.

9. Addition reaction of acetylene:
(1)Acetylene may be hydrogenated in presence of Ni- catalyst at 200°C, or in presence of Pt, Pd or Raney Ni catalyst at room temperature, to form ethylene and then ethane.

⇒ \(\begin{aligned}
& \mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H} \underset{2}{200^{\circ} \mathrm{C}} \mathrm{H}_2 / \mathrm{Ni}=\mathrm{CH}_2 \frac{\mathrm{H}_2 / \mathrm{Ni}}{200^{\circ} \mathrm{C} \downarrow} \\
& \mathrm{H}_3 \mathrm{C} \equiv \mathrm{CH}_3
\end{aligned}\)

(2)Acetylene decolourises the red colour of bromine-water as well as of liquid bromin.

⇒  \(\begin{array}{r}
\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H}+\mathrm{Br}_2 \frac{\mathrm{H}_2 \mathrm{O}}{\longrightarrow} \mathrm{HCBr}=\mathrm{CHBr} \\
\text { (red). } \\
\begin{array}{c}
1,1,2,2 \text {-dibromoethene } \\
\text { (colourless) }
\end{array}
\end{array}\)

⇒  \(\begin{aligned}
& \mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H}+2 \mathrm{Br}_2 \stackrel{\mathrm{H}_2 \mathrm{O}}{\longrightarrow} \mathrm{HCBr}_2-\mathrm{CHBr}_2 \\
& \text { (red) 1,1,2,2-tetrabromoethane } \\
& \text { (colourless) } \\
&
\end{aligned}\)

 

Organic Chemistry Topic B Methane, Ethylene, Acetylene, LPG and CNG Short And Long Answer Type Questions:

 

Question 1. What are the important uses of methane?

Answer:

Important uses of methane

1. ‘Carbon black’ obtained due to cracking of methane is used in making black paint, printing ink and in rubber industries for making motor tyres.
2. Important chemical compounds such as methyl chloride, acetylene, formaldehyde, methanol are prepared from methane.
3. Due to high calorific value of methane (1000 Btu/ft3), it is used as a fuel.

Question 2. Mention some important uses of ethylene.

Answer:

Some important uses of ethylene

1. Ethylene is used in ripening and preservation of fruits.
2. It is used in the preparation of ethylene dichloride, ethylene dibromide, mustard gas (toxic in nature) etc.
3. It is used in the manufacture of plastics such as polythene, polystyrene etc., and synthetic fibres like nylon, terylene etc.
4. A mixture of 80% ethylene and 20% oxygen is used as an anesthetic in surgeries.

Question 3. Mention some important uses of acetylene.

Answer:

Some important uses of acetylene

1. Acetylene is used for producing oxy-acetylene flame, used for cutting steel and other metals.
2. It is used to produce bright illuminating flame in carbide lamps.
3. It is used in the industrial preparation of acetaldehyde, acetic acid, ethyl alcohol, acetone etc.
4. Acetylene is also used in the manufacture of industrial non-inflammable solvents like acetylene tetrachloride (westron, C2H2CI4) and trichloroethylene (westrosol, CI2C = CHCI) used in dissolution of fats, oil and resins.

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Oxy-acetylene flame

 

Question 4. How will you distinguish between the following pairs of compounds? Ethylene and acetylene, ethane and acetylene, ethane and ethylene.

Answer:

Reagent Ethylene Acetylene
Ammoniacal Cu2CI2 solution No precipitate is observed. A red precipitate is formed.

 

Reagent Ethane Acetylene    
Br2/CCI4 solution No change in the colour of bromine solution. The orange-brown colour or bromine solution disappears.

 

Reagent Ethane Ethylene
Br2/CCI4 solution No change in the colour of bromine solution. The orange-brown colour of bromine solution disappears.


Question 5. Write some important uses of LPG.

Answer:

Some important uses of LPG

1. As the calorific value of LPG is very high (29500 kcal/m3)it is used as a fuel for cooking purposes.
2. It is also used as a fuel in vehicles and industries.
3. As boiling point of LPG is quite low, it is also used as a refrigerant.

Question 6. What are the advantages of using LPG as a fuel?

Answer:

The advantages of using LPG as a fuel

1. As the calorific value of LPG is very high, it easily generates large amount of heat which is used up in heating other objects.
2. LPG undergoes complete combustion. So, it does not produce ashes or liberate poisonous gas such as CO during its combustion.
3. Using a regulator, the flow of LPG from the cylinder can be controlled. Hence, its combustion can be controlled depending upon the requirement of heat.
4. LPG cylinders can be conveniently transported to far off places as well.
5. It does not contain carbon monooxide and hence it is not harmful.

Question 7. Which sulphur compound is mixed with LPG? Why is this compound added?

Answer:
1. Ethyl mercaptan (C2H5SH) is mixed with LPG. It emits a very foul smell.
2. The gases constituting LPG are colourless and odourless but are highly imflammable. So, if these gases accidentally leak out of the cylinder, it is not possible to detect them which may lead to fatal accidents. So, as a precautionary measure, ethyl mercaptan is added to LPG as its characteristic foul smell help to detect any gas leakage thereby preventing accidents.

Question 8. Mention some important uses of CNG. Mention one environmental disadvantage of using CNG.

Answer:

Some important uses of CNG.

1. As the calorific value of CNG is very high (21300 Btu/lb), it is widely used as a fuel.
2. CNG causes least air pollution when it is used in vehicles. So, nowadays CNG is extensively used as a fuel in public transport like buses, autos, taxis etc.

Small amount of methane is released into the atmosphere due to the usage of CNG. Methane being a greenhouse gas causes global warming.

Question 9. What-are the advantages of using CNG as a fuel?

Answer:

The advantages of using CNG as a fuel

1. The carbon content of CNG is very low. So, it produces very less amount of carbon particles and CO2 compared to other fuels during its combustion. Thus, CNG causes less air pollution.
2. It has a very high ignition temperature (1350°F). Hence, CNG does not burn easily which makes it safe to use.
3. No poisonous gas and ash are produced during combustion of CNG.
4. The calorific value of CNG (21300 Btu/ lb) is higher than that of diesel and LPG.

Question 10. What are the disadvantages of using CNG as a fuel?

Answer:

The disadvantages of using CNG as a fuel

1. As it is a gaseous fuel, the amount of heat generated by CNG per unit volume is low compared to other fuels.
2. The tanks required to store CNG are usually 3 to 5 times larger than those required for other fuels like diesel.
3. CNG being lighter than air- rises up and rapidly spreads in the atmosphere when it comes out of a cylinder. Consequently, the entire place gets covered by CNG leading to serious explosion.
4. During combustion of CNG, small amount of methane which is a greenhouse gas, is released into the atmosphere.

Question 11. Mention the industrial sources of methane ( CH4).

Answer:

The industrial sources of methane ( CH4)

1. The natural gas obtained from petroleum mines contains large amount of methane (40-90%).
2. Coal gas contains almost 40% (by volume) methane.
3. Methane is found in traces in the gas obtained from coal mines.
4. A mixture of CO2 and H2 or CO and H2 when passed over hot Ni at 250-400°C, methane is produced.

⇒ \(\mathrm{CO}_2+4 \mathrm{H}_2 \underset{250-400^{\circ} \mathrm{C}}{\stackrel{\text { Ni-dust }}{\longrightarrow}} \mathrm{CH}_4+2 \mathrm{H}_2 \mathrm{O} \text {; }\)

⇒ \(\mathrm{CO}+3 \mathrm{H}_2 \underset{250-400^{\circ} \mathrm{C}}{\stackrel{\text { Ni-dust }}{\longrightarrow}} \mathrm{CH}_4+\mathrm{H}_2 \mathrm{O}\)

Question 12. Mention the major industrial sources of ethylene (C2H4).

Answer:

The major industrial sources of ethylene (C2H4)

1. The natural gas obtained from petroleum mines contains almost 20% of ethylene.
2. Ethylene is found in large volumes in coke oven gas.
3. Coal gas contains small amount of ethylene (almost 4%).
4. During cracking (the process by which long-chain hydrocarbons are degraded into smaller hydrocarbons by applying heat) of petroleum, ethylene is produced as a by product.

Question 13. Mention the major indu acetylene (C2H2).

Answer:

The major indu acetylene (C2H2)

1. Coal gas contains traces of acetylene (almost 0.06%)
2. Acetylene is produced by decomposing natural gas (mainly methane) at high temperature.

Question 14. What is LPG? Mention its industrial source?

Answer:

LPG:

1. LPG stands for Liquefied Petroleum Gas. It is a mixture of hydrocarbons of low molecular mass (upto 3-4 C-atoms). The major constituents of LPG are n-butane, propane, isobutane, butene etc. It also contains small amounts of propylene and ethane.
2. LPG is obtained by compressing the crude petroleum during refining into liquid under high pressure. It is stored in steel cylinders.

Question 15. Mention the constituents and industrial sources of CNG.

Answer:

The constituents and industrial sources of CNG

Constituents: The major constituent of CNG (Compressed Natural Gas) is methane (almost 90%). Apart from this, trace amounts of ethane, ethene, propane, butane and low-boiling pentane are also present in CNG.

Industrial sources: Natural gas is obtained above petroleum in petroleum mines and also from the coal mines. This gas is compressed into liquid by applying high pressure.

Question 16. Write with equation what happens when methane reacts with chlorine gas in presence of diffused sunlight.

Answer: In presence of diffused sunlight, methane undergoes substitution reaction with chlorine. In this case, the hydrogen atoms of methane are successively replaced by chlorine atoms one after another to form methyl chloride, methylene chloride, chloroform and carbon tetrachloride.

CH4 + Cl2 → CH3CI (methyl chloride) + HCI
CH3CI + Cl2 → CH2CI2 (methylenechloride) + HCI
CH2CI2 + Cl2 → CHCI3 (chloroform) + HCI
CHCI3 + Cl2 → CCI4 (carbon tetrachloride) + HCI

Question 17. Write down the hydrogenation reaction of ethylene specifying suitable conditions and chemical equation.

Answer: Hydrogen adds to the double bond of ethylene molecule at ordinary temperature and pressure in the presence of finely divided platinum or palladium or Raney nickel or at a temperature of about 200-300°C in the presence of finely divided nickel catalyst to produce ethane.

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Hydrogenation Reaction Of Ethylene And Chemical Equation

 

Question 18. What happens when ethylene gas is passed through bromine dissolved in carbon tetrachloride or in chloroform? Give equation. Or, How will you prove that ethylene is an unsaturated compound? Or, Give an example of addition reaction of ethylene.

Answer: When ethylene gas is passed through bromine dissolved in carbon tetrachloride ( CCI4) or in chloroform (CHCI3), the orange-brown colour of the solution is decolourised due to the formation of a colourless compound, ethylene dibromide or 1,2-dibromoethane. This reaction proves that ethylene is an unsaturated compound.

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry

 

Question 19. Write a short note on polymerisation of ethylene.

Answer:

Polymerisation of ethylene

When ethylene is heated at 150 – 200°C in the presence of oxygen or peroxide catalyst under a very high pressure (1500-2000 atm), a large number of ethylene molecules combine with each other to form a solid compound of high molecular mass (approx. 20000) called polyethylene or polythene. This reaction is known as polymerisation of ethylene.

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Polymerisation Of Ethylene

 

Question 20. Write down the hydrogenation reaction of acetylene specifying the suitable conditions and chemical equation.

Answer: Hydrogen reacts with acetylene at ordinary temperature in presence of Raney nickel or powdered platinum or palladium catalyst or at a temperature of about 200 – 300°C in presence of powdered nickel catalyst to produce ethane. The reaction occurs in two steps. In the first step, one molecule of hydrogen adds to acetylene to form ethylene and in the second step, another molecule of hydrogen adds to ethylene to form ethane.

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Polymerisation Of Ethylene

Question 21. Which of the following hydrocarbons will participate in addition reactions— C4H10 ,C3H4 ,C3H6

Answer: Only unsaturated hydrocarbons participate in addition reactions. Among the given hydrocarbons, C3H6 (an alkene) and C3H4 (an alkyne) are unsaturated compounds and hence, undergo addition reactions. On the other hand,  C4H10 (an alkane) being a saturated compound does not undergo addition reaction.

Wbbse Class 10 Organic Compounds

Question 22. How will you prove that acetylene is an unsaturated compound? Or, What happens when an excess amount of acetylene gas is passed through bromine? Give equation.

Answer: When acetylene gas is passed through orange- brown coloured bromine water, 1,2- dibromoethene or acetylene dibromide is formed and consequently, the colour of bromine water is discharged. This reaction proves that acetylene is an unsaturated compound.

HC = CH + Br2 → CHBr = CHBr
(orange-brown solution)  1,2-dibromo ethene (colourless)

Question 23. Three cylinders separately contain methane, ethylene and acetylene. How will you identify the gases?

Answer:

Three cylinders separately contain methane, ethylene and acetylene.

At first, the three gases are separately passed through ammoniacal cuprous chloride solution. The gas which produces a red precipitate is acetylene. After that, the two remaining gases are separately passed through bromine dissolved in CCI4 solution. The gas which turns orange-brown solution of bromine colourless is ethylene. Thus, the remaining gas is definitely methene.

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry

Question 24. what happens when methane is combusted in the presence of oxygen? Give balanced equations.

Answer: Methane burns with a light blue flame in excess air or oxygen and produces carbon dioxide, water vapour and huge heat is evolved.

⇒ \(\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H} \stackrel{\mathrm{CuCl}_2}{\longrightarrow} \mathrm{H}-\underset{\text { red ppt }}{\mathrm{C} \equiv \stackrel{\ominus}{\mathrm{C}} \mathrm{Cu}^{\oplus} \downarrow}\)

Question 25. What is Will-o’-the-wisp?

Answer:

Will-o’-the-wisp

Methane is formed in marshy lands due to the bacterial decomposition of organic matter. Moreover, phosphine (PH3) and phosphorous tetrahydride (P2H4) are also formed as a result of the putrefaction of animal bodies. P2H4 rapdily burns in the air.

So when the mixture of CH4, PH3 and P2H4 comes in contact with air, P2H4 sets the gas mixture on fire and the heat produced causes methane to burn with a light blue flame. As a result, an intermittent source of light is produced. This is known as ‘Will-o’-the-wisp’.

Wbbse Class 10 Organic Compounds

Question 26. How will you prepare ethylene from acetylene?

Answer: In the presence of Lindler’s catalyst, acetylene combines with only one molecule of hydrogen to form ethylene.

⇒ \(\mathrm{HC} \equiv \mathrm{CH}+\mathrm{H}_2 \frac{\mathrm{Pd}-\mathrm{CaCO}_3 / \mathrm{Pb}(\mathrm{OAc})_2}{\text { Lindler’s catalyst }} \mathrm{H}_2 \mathrm{C}=\mathrm{CH}_2)\)

Question 27. A’ and ‘B’ are two unsaturated hydrocarbons with two carbon atoms in each. In reaction with bromine, each molecule of ‘A’ combines with 1 molecule of bromine and while each molecule of ‘B’ combines with 2 molecules of bromine. Write down the structure of ‘A’ and ‘S’. Write down the balanced equation for the reaction of ‘6’ with bromine.

Answer: Unsaturated hydrocarbons with two carbon atoms are ethylene and acetylene. Since each molecule of ‘A’ combines with 1 molecule of bromine, therefore ‘A’ is ethylene (CH3 = CH2). Again since each molecule of ‘6’ combines with 2 molecules of bromine, therefore ‘S’ is acetylene (HC ≡ CH).

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry

 

Organic Chemistry Topic B Methane, Ethylene, Acetylene, LPG and CNG Answer In Brief:

 

Question 1. What is carbon black?
Answer: At 1000°C, methane decomposes to form fine particles of carbon which is known as carbon black.

⇒ \(\mathrm{CH}_4 \stackrel{1000^{\circ} \mathrm{C}}{\longrightarrow} \mathrm{C}+2 \mathrm{H}_2 \uparrow\)

Question 2. What are the uses of carbon black?
Answer: Carbon black is used in the manufacture of tyres, typewriter ribbons, printing ink, shoe polish etc.

Question 3. Which member of the alkane homologous series is the major constituent of natural gas?
Answer: Methane (CH4) belonging to the alkane homologous series is the major constituent of natural gas.

Question 4. Give an example of a hydrocarbon which is also a greenhouse gas.
Answer: Methane (CH4) is a hydrocarbon as well as a greenhouse gas.

Wbbse Class 10 Organic Compounds

Question 5. Which hydrocarbon is used in the industrial preparation of formaldehyde?
Answer: Methane (CH4) is used in the industrial preparation of formaldehyde.

Question 6. Which hydrocarbon is used in the manufacture of industrial non-inflammable solvents namely Westron and Westrosol (used to dissolve fats, oils, resins etc.)?
Answer: Acetylene (C2H2) is used in the manufacture of industrial non-inflammable solvents namely Westron and Westrosol.

Question 7. Write with equation what happens when methane undergoes combustion in the presence of sufficient oxygen.
Answer: When methane undergoes combustion it burns with a pale bluish non-luminous flame in presence of sufficient oxygen or air to produce CO2 and water vapour.

⇒ \(\begin{array}{r}
\mathrm{CH}_4+2 \mathrm{O}_2 \rightarrow \mathrm{CO}_2+2 \mathrm{H}_2 \mathrm{O}+\text { heat } \\
\left(213 \mathrm{kcal} \cdot \mathrm{mol}^{-1}\right)
\end{array}\)

Question 8. Name the catalyst used in the addition reaction between ethylene and hydrogen.
Answer: Pt, Pd or Raney nickel is used as the catalyst in the addition reaction between ethylene and hydrogen.

Question 9. Under what conditions do the H-atoms of methane gets replaced by chlorine atoms in stepwise substitution reaction?
Answer: When chlorine reacts with methane in the presence of diffused sunlight the H-atoms of methane gets successively replaced by chlorine atoms in stepwise substitution reaction.

Question 10. What is the main component of marsh gas?
Answer: Main component of Marsh gas is methane (CH4).

Question 11. Write down the formula of the organic compound formed in the first step of the substitutional reaction of methane with chlorine.
Answer: Formula of the compound is CH3CI (methyl chloride).

Question 12. Which gas is responsible for Will- ‘O’-the wisp?
Answer: Methane gas (CH4) along with phosphine (PH3) and diphosphane (P2H4) are responsible for Will- ‘O’-the wisp.

Wbbse Class 10 Organic Compounds

Question 13. Which one undergoes addition reaction, saturated or unsaturated hydrocarbon?
Answer: Unsaturated hydrocarbon undergoes addition reaction.

Question 14. How will you identify wheather an organic compound is unsaturated or not?
Answer: If the red colour of bromine water decolourises in reaction with the sample organic compound, it can be said that the sample organic compound is unsaturated.

Question 15. CaC2 + 2H2O → A + Ca(OH)2; Identify ‘A’.
Answer: ‘A’ is acetylene, HC = CH.

Question 16. Write down the name of the compound formed when acetylene gas is passed through red coloured bromine water.
Answer: 1,2-dibro methene (CHBr = CHBr)

Question 17. What is the main component of LPG?
Answer: Butane (C4H10).

Question 18. Mention the use of LPG.
Answer: LPG is used as fuel in cooking and industrial purpose.

Question 19. Which bad-smelling component is mixed with LPG?
Answer: Ethyl mercaptan ( C2H5SH)

Question 20. What is the industrial source of CNG?
Answer: The source is usually shale rock far beneath the earth’s surface. Again the trapped gas in petroleum mines is CNG.

Question 21. Which one of petrol and CNG causes comparatively lower air pollution when used as fuel for vehicles?
Answer: CNG causes comparatively lower pollution.

Question 22. Mention the use of CNG.
Answer: CNG is used as fuel in bus, taxi, auto rickshaws etc.

Organic Chemistry Topic B Methane, Ethylene, Acetylene, LPG and CNG Fill In The Blanks:

Physical Science Class 10 West Bengal Board

Question 1. The characteristic odour of LPG is due to the presence of _______
Answer: Ethyl mercaptan

Question 2. Methane gas is used as a fuel because of its high ______
Answer: Calorific value

Question 3. At high temperatures, natural gas is decomposed to produce _______
Answer: Acetylene

Question 4. _______ is formed when all the hydrogen atoms in methane are replaced by chlorine atoms.
Answer: Carbon tetrachloride

Question 5. The number of organic compounds formed in the reaction between methane and chlorine is _______
Answer: 4

Question 6. The temperature of the oxy-acetylene flame is ______°C.
Answer: 3000

Question 7. The major constituent of LPG is ______
Answer: Butane

Question 8. To reduce air pollution, _______ is used as an alternative fuel nowadays in buses, taxis, auto-rickshaws and other vehicles.
Answer: CNG

Question 9. In the presence of excess oxygen, methane burns with a non-luminous, pale _____ flame.
Answer: Blue

Question 10. In addition reaction with hydrogen, each molecule of ethylene combines with _____ molecule of hydrogen.
Answer: One

Wbbse Class 10 Organic Compounds

Question 11. At normal temperature, ethylene is a while polythene is a ______ while polythene is a ______
Answer: Gas, solid

Question 12. The component of Marsh gas which ignites in contact with air is ______
Answer: P2H4

Question 13. 3’H’ atoms of methane when substituted by 3’CI’ atoms, ______ is formed.
Answer: Chloroform

Question 14. Full form of LPG is ______
Answer: Liquefied Petroleum Gas

Question 15. Full form of CNG is ______
Answer: Compressed Natural Gas

 

Organic Chemistry Topic B Methane, Ethylene, Acetylene, LPG and CNG State Whether True Or False:

Physical Science Class 10 West Bengal Board

Question 1. Methane usually participates in additional reactions.
Answer: False

Question 2. A mixture of methane and oxygen explodes when it comes in contact with fire.
Answer: True

Question 3. The decomposition of acetylene at a temperature of about 1000°C produces fine particles of carbon called carbon black.
Answer: False

Question 4. LPG stands for Liquid Petroleum Gas.
Answer: False

Wbbse Class 10 Organic Compounds

Question 5. Acetylene is used to produce illuminating flame in carbide lamps.
Answer: True

Question 6. 10% methane is present in coal gas (by volume).
Answer: False

Question 7. The smell of H2S can be smelled in leakage of the LPG cylinder.
Answer: False

Question 8. CNG produces comparatively lower pollutants than LPG.
Answer: True

 

Organic Chemistry Topic C Polymer, Ethyl Alcohol, Acetic Acid And Denatured Spirit Synopsis:

 

1. A chemical reaction in which a number of simple molecules react to form a larger molecule of high molecular mass is called a polymerisation reaction. The large molecule formed in the reaction is called polymer and the small molecules forming the repeating units in the polymer are called monomers. For example, polyethene, PVC, and Teflon.

2. Non-biodegradable synthetic polymers create different environmental hazards. As the manufacture of biodegradable polymers is still not cost-effective yet, use of natural polymers such as cotton, jute, wood, paper etc., should be encouraged.
3. Ethyl alcohol, acetic acid and denatured spirit have different commercial utilities.

Wbbse Class 10 Physical Properties Of Organic Compounds

4. Uses of acetic add:
(1)Acetic acid is used to prepare white lead, and acetone. 0 5-8% aqueous solution of acetic acid is used to preserve fish, meat etc.

5. Methylated spirit or denatured spirit: Poisonous methanol (10%), a small amount of pyridine, naphtha, copper sulphate. etc.

6. Some polymers and their monomers:

Polymer Name and formula of the monomer Uses of polymer
1. Polythene or polyethene (PE) Ethene or Ethylene (CH2 = CH2) 1. Used to prepare carry bags,2. used to prepare water pipes, water tanks, bottles, buckets, mugs etc.
2. Polyvinyl chloride(PVC) Vinyl Chloride 1. To prepare a false ceiling, 2. to make an insulator of wire, 3. used to prepare an inner side of the refrigerator.
3. Polytetrafluroethylene (PTFE) Tetrafluoroethylene(F2C = CF2) 1. prepare non-stick utensils,2. used as insulators in electrical goods, 3. To prepare several apparatus in the chemical lab.

 

Are mixed with ethyl alcohol to make it poisonous and non-drinkable. This mixture is termed as methylated spirit or denatured spirit.

7. Uses of denatured spirit:
1. Used as a solvent of paint or varnish.
2. Used as the fuel of spirit lamp and stove.

Physical Science Class 10 West Bengal Board

Organic Chemistry Topic C Polymer, Ethyl Alcohol, Acetic Acid And Denatured Spirit Short And Long Answer Type Questions:

 

Question 1. Which compound is formed due to the polymerisation of ethylene? How does it differ from ethylene in terms of its properties?

Answer: Due to polymerisation of ethylene, the polymer polythene or polyethene is formed.

The difference in properties of ethylene and polythene are as follows—

Ethylene Polythene
1. Ethylene is a gas at ordinary temperature. 1. Polythene is solid at ordinary temperature.
2. The molar mass of ethylene is constant. Its value is 28. 2. Polythene is formed by the combination of numerous ethylene molecules. Thus, its molar mass is very high (approx. 20000).
3. Being a gas, the molar volume of ethylene at STP is very high (22.4 L). 3. Being a solid, the molar volume of polythene at STP is very low.

 

Question 2. What are biodegradable and non-biodegradable polymers? Give examples.

Answer:
1. The polymers which are degraded by the enzymatic action of environmental microorganisms (such as bacteria, fungi etc.) to form simple molecules (such as CO2, H2O etc.) are known as biodegradable polymers.’

Example: Polymers obtained from animals and plants such as carbohydrates (cellulose, starch), protein, nucleic acids etc.

2. The polymers which are not degraded by the enzymatic action of environmental microorganisms (such as bacteria, fungi etc.) to form simple molecules such as CO2, H2O etc., are known as non-biodegradable polymers.

Example: Synthetic polymers such as polyethene, PVC, polystyrene, Teflon etc.

Physical Science Class 10 West Bengal Board

Question 3. Biodegradable polymers do not cause environmental pollution—Explain with a suitable example.

Answer: Biodegradable polymers are degraded into simpler compounds such as CO2, H2O etc., due to the enzymatic action of different microorganisms (bacteria, fungi etc.) present in the environment. These compounds are not hazardous to the environment and thus, biodegradable polymers do not cause environmental pollution.

For example, cotton, straw, paper and wood are biopolymers or polymers originating from plant sources. Cellulose present in these biopolymers is degraded by the enzymatic action of microorganisms into compounds which are not harmful to the environment.

Question 4. How do non-biodegradable polymers cause environmental pollution?

Answer:
1. Most synthetic polymers are non-biodegradable in nature and hence, they are not easily decomposed. These polymers accumulate in the soil and prevent the free flow of air and water in the soil. This makes the soil infertile and unsuitable for agriculture.

Deposition of these polymers in the soil leads to the formation of toxic chemical compounds due to weathering which in turn adversely affects the useful soil microorganisms. Accumulation of plastics also blocks the drains and sewage canals which makes the sewage system ineffective.

2. Combustion of synthetic polymers produces poisonous gases like CO, SO2, NO2 etc., and causes air pollution.
3. PVC polymers may sometimes contain free vinyl chloride monomer. When water pipes, water tanks etc., made of PVC get damaged due to friction, the monometer(vinyl chloride) may mix with water, Vinyl chloride is carcinogenic in nature.

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Environmental Pollution Due To Non-Biodegradable Polymers

 

Physical Science Class 10 West Bengal Board

Question 5. What measures should be adopted to prevent pollution caused by non-biodegradable polymers?

Answer:

1. Extensive use of synthetic polymers such as plastics, polythene, PVC etc., should be reduced.
2. Recently, it has been possible to prepare some synthetic biodegradable polymers such as Nylon- 2, Nylon-6, PHBV etc. However, the cost of production of these polymers is very high.
3. Natural polymers such as paper, cotton, jute etc., are biodegradable in nature. Thus, the use of jute and paper for packaging purposes should be encouraged. The government must also initiate awareness campaigns for people to encourage the use of natural polymers.
4. Remoulding of plastic wastes into other useful substances by recycling is another way to control pollution caused by non-biodegradable polymers.

Question 6. Discuss some important uses of ethyl alcohol.

Answer:

Some important uses of ethyl alcohol

1. Ethyl alcohol is used as a solvent for resins, soaps, varnishes, rayons, scents, pigments, synthetic rubbers, synthetic fibres, medicines, etc. % 2. It is used in the preparation of ether, ethyl esters, ethyl halides, chloroform, acetic acid, ethylene, methylated spirit etc.
3. Power alcohol which is used as an automobile fuel is prepared by mixing ethyl alcohol with petrol.
4. In cold countries, a mixture of water and ethanol is used as the anti-freezing agent in the radiators of motor vehicles.

Question 7. Mention some important uses of acetic acid.

Answer:

Some important uses of acetic acid

1. Glacial acetic acid (anhydrous) is used as a solvent for many organic compounds. 0 Acetic acid is used to prepare chemical compounds such as acetone, ethyl acetate, acetic anhydride, acetyl chloride etc.
2. Cellulose acetate, used for the preparation of photographic films and synthetic fibres (rayon), is prepared from acetic acid.
3. Vinegar (5-8% aqueous solution of acetic acid) is used as a preservative for fish, meat, etc., and also for making pickles and chutneys.

Question 8. What are polymers and monomers? Give example.

Answer:

Polymers and monomers

The giant molecules of high molecular mass formed by the polymerisation of a large number of small molecules, linked together in long chains of varying lengths are called polymers. The small molecules forming the repeating units in polymers are called monomers.

Physical Science Class 10 West Bengal Board

Example: A large number of ethylene molecules combine with each other to form polyethene. Hence, polyethene is the polymer while ethylene is its monomer.

Question 9. Write the name and structural formula of the monomer of polythene. Write some lines of polythene.

Answer: The monomer of polythene is ethene or ethylene and its structural formula is CH2 = CH2.

Uses of polythene: It is used as a packaging material and in the manufacture of carry bags, water pipes, water tanks, bottles, buckets, and window nets and as electrical insulation for being a non-conductor of electricity.

Question 10. Write the name and structural formula of the monomer of polyvinyl chloride (PVC). Write some uses of PVC.

Answer: The monomer of polyvinyl chloride (PVC) is vinyl chloride and its structural formula is CHCI.

Uses of PVC: It is used in the manufacture of electrical wires and cable insulation, water pipes, water tanks, raincoats, artificial flooring, handbags, tubings and hoses for corrosive materials etc.

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Articles Made Of Polythene

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Articles Made Of Teflon

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry Articles Made Of PVC

 

Question 11. Write the name and structural formula of the monomer of polytetrafluoroethylene (PTFE) or Teflon. Write some uses of Teflon.

Wbbse Class 10 Physical Science Solutions

Answer: The monomer of Teflon is tetrafluoroethylene and its structural formula is F2C — CF2.

Uses Of Teflon: It is used in making non-stick cookware, as an insulating cover in electrical appliances, in making pipes and tanks for carrying corrosive substances and for making laboratory apparatus.

Question 12. Biodegradable polymers are more eco-friendly than non-biodegradable polymers. Explain.

Answer:

Biodegradable polymers are more eco-friendly than non-biodegradable polymers.

Uncontrolled use of non-biodegradable polymers is a major cause of environmental pollution. So, the use of natural polymers such as cotton, wood, paper, jute etc., should be encouraged until and unless the cost of manufacture of biodegradable polymers can be minimised. Jute and paper should be extensively used for packaging. Jute bags instead of plastic bags should be used for carrying things. As these are biodegradable polymers, they do not cause pollution.

Wbbse Class 10 Physical Science Solutions

Question 13. Write the equation of what happens when absolute ethanol is heated with excess concentrated  H2SO4 at 170°C. What wifi happens if the reaction is carried out with excess ethanol instead of excess acid?

Answer: When absolute ethanol is heated with excess concentrated  H2SO4 at 170°C, ethanol undergoes dehydration to produce ethene.

CH3CH2OH + H2SO4 (conc.) → CH2 = CH2 (ethene) + H2O
(excess)

If the reaction is carried out in presence of excess ethanol instead of excess acid at a temperature of 140°C, then diethyl ether is produced instead of ethene.

CH3CH2OH + HOCH2CH3 → CH3CH2 —O—CH3CH2 + H2O

Question 14. Write with an equation of what happens when sodium hydroxide reacts with acetic acid.

Answer: Acetic acid reacts with sodium hydroxide solution to form sodium acetate or sodium ethanoate (CH3COONa) and water.

CH3COOH + NaOH → CH3COONa + H2O

Question 15. Write with an equation what happens when sodium bicarbonate reacts with acetic acid.

Answer: Acetic acid (CH3COOH) reacts with sodium bicarbonate (NaHCO3) to form sodium acetate, water and carbon dioxide and the latter comes out of the reaction mixture as effervescence.

CH3COOH + NaHCO3 → CH3COONa + CO2 ↑ + H2O

Wbbse Class 10 Physical Science Solutions

Question 16. How will you distinguish between ethanol and acetic acid using sodium bicarbonate?

Answer: Ethanol does not react with sodium bicarbonate but, acetic acid reacts with sodium bicarbonate to form carbon dioxide which comes out of the solution as effervescence.

CH3CH2OH + NaHCO3 → No reaction
CH3COOH + NaHCO3→ CH3COONa + CO2 ↑+ H2O

Question 17. What is esterification? Describe the esterification reaction of ethyl alcohol and acetic acid along with a suitable equation.

Answer:

Esterification

1. In presence of a suitable catalyst such as concentrated H2SO4 or dry HCI, carboxylic acids react with dry alcohols to produce esters and water. This reaction is known as the esterification reaction.
2. When dry ethyl alcohol (CH3CH2OH) is heated with acetic acid (CH3COOH) in presence of concentrated H2SO4 which acts as the catalyst, ethyl acetate (CH3COOCH2CH3) having a fruity smell is formed.

 

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry

 

Question 18. What are the physiological effects of consuming ethyl alcohol?

Answer: Consumption of limited amount of ethyl alcohol may act as a mild stimulant. However, if it is consumed in large quantities, it may lead to different physiological problems such as headache, nausea, reluctance to work, incoherence of speech, unconsciousness etc. Regular consumption of ethyl alcohol may lead to addiction which affects the liver and kidneys and may eventually lead to death.

Wbbse Class 10 Methanol Formula

Question 19. Briefly discuss the toxic effects of methanol.

Answer:

The toxic effects of methanol

Methanol is a highly toxic compound. Consumption of even a small amount of methanol may be fatal. It gets oxidised to form formaldehyde in the liver cells which rapidly reacts with certain components responsible for the formation of the cells. As a result, the protoplasm of the cell gets coagulated. Apart from this, methanol also damages the optic nerves which may cause blindness. Excess intake of methyl alcohol may even cause death.

Question 20. What is a methylated spirit or denatured spirit? Write its uses.

Answer: In order to prevent the use of ethanol as a beverage, it is made unfit for consumption by adding highly poisonous methyl alcohol (up to 10%) along with small amounts of certain compounds having a bitter taste such as pyridine, copper sulphate, naphtha etc. This mixture is known as methylated spirit or denatured spirit.

Uses: It is used as a solvent for paints and varnishes, as a fuel and in lighting stoves.

Wbbse Class 10 Methanol Formula

Question 21. Write down the differences between polymer and monomer.

Answer:

The differences between polymer and monomer are as follows—

Topic Polymer Monomer
1. Definition Giant molecules formed by the chemical union of a large number of small molecules, Jinked together in long chains of varying lengths are called polymers. The small molecules forming the repeating units in polymers are called monomers.
2. Molecular weight The molecular weight of polymers is much higher than the corresponding monomers. The molecular weight of monomers is less compared to that of polymers.
3. Formula The formula varies with the number of repeating units and the process of polymerisation. The formula of the monomer is fixed.
4. Example Polytetrafluoroethylene (PTFE) or Teflon The monomer of Teflon is tetrafluoroethylene (F2C = CF2)

 

Question 22. Which one between jute and polythene used in packaging is eco-friendly and why?

Answer: Jute is eco-friendly. Because jute is the natural polymer of carbohydrate molecule called cellulose. Being biodegradable, jute easily decomposes and mixes with soil, causing no harm to the environment. But polythene is a non- biodegradable polymer and hence does not mix with soil after use and causes environmental pollution in several ways.

Question 23. Identify A, B and C:


WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry

Answer:

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry

 

Question 24. The molecular formula of an organic compound is   C2H4O2. The compound is soluble in water and on the addition of NaHCO3 in the aqueous solution of the compound, CO2 gas evolved. Identify the compound. Write down the condition and balanced equation of the reaction of the organic compound with ethanol.

Answer:
1. Since the compound is organic, water-soluble and produces CO2 in reaction with NaHCO3, the compound must be a carboxylic acid i.e., the —  COOH group is present as a functional group.

Since the formula of the compound is C2H4O2 so — CH3 group must be added with — COOH.

The compound is CH3COOH i.e., acetic acid.

Wbbse Class 10 Methanol Formula

2. In presence of heat and cone. H2S04, acetic acid reacts with ethyl alcohol producing sweet-smelling ethyl acetate ester and water.

WBBSE Solutions For Class 10 Physical Science And Environment Physical And Chemical Properties Of Elements Organic Chemistry

 

Organic Chemistry Topic C Polymer, Ethyl Alcohol, Acetic Acid And Denatured Spirit Answer In Brief:

 

Question 1. Which polymer is present in plant fibres such as cotton, jute etc.?
Answer: Plant fibres such as cotton, jute etc., are made of the polymer, cellulose.

Question 2. What is bio pool?
Answer: The trade name for polyhydroxy butyrate (PHB) is bio pool. It is an eco-friendly and biodegradable synthetic polymer.

Question 3. Give an example of a biodegradable synthetic polymer.
Answer: Polyhydroxybutyrate is a biodegradable synthetic polymer.

Question 4. What are the uses of bio pool?
Answer: Biopol is widely used to make single-use products such as disposable cups, shaving razors, surgical threads etc.

Question 5. What is rectified spirit?
Answer: A solution of 95.6% ethanol and 4.4% water is known as rectified spirit.

Question 6. Give an example of an organic compound which turns blue litmus red.
Answer: Acetic acid turns blue litmus red.

Question 7. Which organic compound is used to make pickles and chutneys?
Answer: Vinegar (5-8% aqueous solution of acetic acid) is used to make pickles and chutneys.

Wbbse Class 10 Physical Properties Of Organic Compounds

Question 8. What is vinegar?
Answer: A 5-8% aqueous solution of acetic acid is commonly known as vinegar.

Wbbse Class 10 Methanol Formula

Question 9. How do biopolymers decompose in the natural environment?
Answer: Biopolymers decompose into simple molecules (like  CO2, H2O etc.) by the action of different microorganisms (fungi, bacteria etc.) present in the natural environment.

Question 10. Write down the name of the monomer of polythene.
Answer: The monomer of polythene is ethene or ethylene.

Question 11. What is PVC?
Answer: PVC or polyvinyl chloride is the polymer of vinyl chloride (CH2 = CH — Cl).

Question 12. Mention the use of polyvinyl chloride.
Answer: PVC is used to prepare corrugated roofing material.

Question 13. Name a polymer which is used to prepare raincoats, sandals or gumboots.
Answer: PVC or polyvinyl chloride.

Question 14. Write down the full form of PTFE.
Answer: Polytetrafluoroethylene.

Question 15. Mention the use of polytetrafluoroethylene.
Answer: Polytetrafluoro ethylene is used to prepare non-stick cooking utensils.

Question 16. Name two natural polymers.
Answer: Cellulose and protein.

Question 17. Which type of polymer is protein?
Answer: Protein is a biodegradable natural polymer.

Question 18. Name the monomer of the protein.
Answer: The monomer of protein is an amino acid.

Question 19. Mention an use of ethyl alcohol.
Answer: Ethyl alcohol is used to prepare rectified spirit (96.5% ethanol and 4.4% H2O) which is used as an antiseptic.

Question 20. What is formed when ethyl alcohol is dehydrated by cone H2SO4?
Answer: Ethylene is formed when ethyl alcohol is dehydrated by the cone. H2SO4 .

Question 21. Write down the formula of a compound which can form ester in reaction with ethanol.
Answer: Acetic acid (CH3COOH)

Question 22. Which gas is evolved when NaHCO3 is added to acetic acid?
Answer: Carbon dioxide (CO2)

Question 23. Which compounds are formed in the reaction of CH3COOH with NaOH?
Answer: Sodium acetate (CH3COONa) and water (H2O).

Question 24. What is glacial acetic acid?
Answer: Acetic acid that contains a very low amount of water (less than 1%) is called anhydrous acetic acid or glacial acetic acid. The reason it is called glacial is that it solidifies into white solid acetic acid crystals at 16.7°C.

 

Organic Chemistry Topic C Polymer, Ethyl Alcohol, Acetic Acid And Denatured Spirit  Fill In The Blanks:

 

Question 1. Ethyl alcohol reacts with metallic sodium at ______ temperature to liberate _______ gas.
Answer: Ordinary, hydrogen

Question 2. The monomer of Teflon is _____
Answer: Tetrafluoroethylene

Question 3. ______ is mixed with petrol to produce power alcohol which is used as an automobile fuel.
Answer: Ethanol

Question 4. Ethyl alcohol on dehydration produces _____
Answer: Ethylene

Question 5. A mixture of 80% _____ and 20% ______ is used as an anaesthetic during surgeries.
Answer: Ethylene, oxygen

Question 6. Among all alcohols, _________ is toxic in nature.
Answer: Methanol

Question 7. Iodine dissolved in _______ is known as a tincture of iodine.
Answer: Ethyl alcohol

Question 8. The monomer of PVC is _______
Answer: Vinyl chloride

Question 9. ______ is used to prepare gramophone records.
Answer: PVC

Question 10. The polymer of phenol and formaldehyde is _______
Answer: Bakelite

Question 11. Ethyl alcohol reacts with metallic sodium at _______ temperature to form gas.
Answer: Normal, hydrogen

Question 12. _____ is mixed with petrol to form the fuel for a motor car called power alcohol.
Answer: Ethanol

Question 13. Almost ______ ethyl alcohol is present in rectified spirit.
Answer: 95.6%

Question 14. _______ can cause blindness by causing harm to the optic nerve.
Answer: Methanol

 

Organic Chemistry Topic C Polymer, Ethyl Alcohol, Acetic Acid And Denatured Spirit State Whether True Or False:

 

Question 1. Oxygen or peroxide is used as the catalyst during the polymerisation of ethylene.
Answer: True

Question 2. The monomer of the polymer Teflon is vinyl chloride.
Answer: False

Question 3. Methanol on entering the body can damage the optic nerves.
Answer: True

Question 4. Polystyrene and polyethene are examples of non-biodegradable polymers.
Answer: True

Question 5. Petrol mixed with alcohol along with a cosolvent like benzene is called power alcohol.
Answer: True

Question 6. The basicity of acetic acid is 2.
Answer: False

Question 7. In spite of being an organic compound, ethyl alcohol is soluble in water due to its formation of hydrogen bonds with water molecules.
Answer: True

Question 8. The reaction between an alcohol and an aldehyde to form an ester in presence of concentrated sulphuric acid is called an esterification reaction.
Answer: False

Question 9. Teflon is used to prepare non-stick frying pans.
Answer: True

Question 10. Ethanol causes harm to the liver.
Answer: True

Question 11. Denatured spirit is used as a solvent of organic substances.
Answer: True

Question 12. Methylated spirit is poisonous due to the presence of methanol.
Answer: True

Miscellaneous Type Questions Match The Column:

 

Question 1.

Column A Column B
Dimethyl ether and ethyl alcohol 1. Chain isomers
n-propyl alcohol and propan-2-ol 2. Functional group isomers
n-pentane, isopentane and neopentane 3. Ring-chain isomers
Propene and cyclopropane 4. Positional isomers

 

Answer:
Dimethyl ether and ethyl alcohol: 2. Functional group isomers
n-propyl alcohol and propan-2-ol: 4. Positional isomers
n-pentane, isopentane and neopentane: 1. Chain isomers
Propene and cyclopropane: 3. Ring-chain isomers

Question 2.

Column A Column B
Hydrogenation of ethylene 1. Undergoes substitution reactions
C4H10 2. Prepared acetic acid and methane from their constituent elements
Kolbe and Berthelot 3.  Alternative name for alkanes
Paraffin 4.  Ethane is formed as the product

 

Answer:
Hydrogenation of ethylene: 4.  Ethane is formed as the product
C4H10 1. Undergoes substitution reactions
Kolbe and Berthelot: 2. Prepared acetic acid and methane from their constituent elements
Paraffin: 3.  Alternative name for alkanes

Question 3.

 

Column A Column B
Biopol 1. Natural polymer
Vinegar 2. Commercial name of tetrafluoroethylene
Teflon 3. Commercial name of polyhydroxybutyrate
Cellulose 4. 5-8% aqueous solution of acetic acid

 

Answer:
Biopol: 3. Commercial name of polyhydroxybutyrate
Vinegar: 4. 5-8% aqueous solution of acetic acid
Teflon: 2. Commercial name of tetrafluoroethylene
Cellulose: 1. Natural polymer

WBBSE Solutions for Class 10 Physical Science and Environment

 

 

 

 

 

 

 

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