WBCHSE Class 11 Physics For First And Second Law Of Thermodynamics Multiple Choice Questions

First And Second Law Of Thermodynamics Multiple Choice Questions And Answers

Question 1. When a bullet of 6 g mass hits a target at a speed of 400 m · s^-1, 70% of its energy is converted into heat. The value of heat generated is

1. 336 cal
2. 80 cal
3. 3.36 x 10⁵ cal
4. 80000 cal

Answer: 2. 336 cal

Question 2. Water drops from a height of 40 m in a waterfall. If 75% of its energy is converted to heat and absorbed by the water, the rise in temperature of the water will be

1. 0.035°C
2. 0.07°C
3. 0.35°C
4. 0.7°C

Answer: 2. 0.07°C

Question 3. The amount of work done to convert 1 g of ice at 0°C into steam at 100 °C is

1. 756 J
2. 2688 J
3. 3024 J
4. 171.4 J

Answer: 3. 3024 J

Question 4. 169 J energy is required to transform 1g(1cm³) of water into steam at 1 atm pressure. If the latent heat of vaporization of water is 540 cal · g^-1, the volume of that steam will be

1. 1560 cm³
2. 1671 cm³
3. 1571cm³
4. 1600 cm³

Answer: 2. 1671 cm³

Question 5. A man of mass 90 kg gains 10⁵ cal of heat from his food intake. If his digestive ability is 28%, how much height can he climb up to?

1. 1333 m
2. 133.3 m
3. 13.33 m
4. 1.333 m

Answer: 2. 133.3 m

Question 6. Which of the following quantities does not indicate any thermodynamic state of a substance?

1. Volume
2. Temperature
3. Pressure
4. Work

Answer: 4. Work

Question 7. The internal energy of a substance means

1. The kinetic energy of the substance
2. The kinetic energy of the molecules of the substance
3. The sum of its kinetic and potential energies
4. The sum of kinetic and potential energies of the molecules of the substance

Answer: 4. The sum of kinetic and potential energies of the molecules of the substance

Question 8. If the average kinetic energy of the molecules of a certain mass of a gas decreases, then

1. The gas becomes hot
2. The gas becomes cold
3. The gas expands
4. The gas contracts

Answer: 2. The gas becomes cold

Question 9. If the volume of a gas of a certain mass changes from 1 L to 0.5 L at a constant pressure of 10⁵ N · m^-2, work done by the gas will be

1. 50000 J
2. -50000 J
3. 50 J
4. -50 J

Answer: 4. -50 J

Question 10. The internal energy of a system is U₁. In a process, work done by the system is W, and heat accepted by the system is Q. At the end of the process, the internal energy of the system is

1. U₁ + Q-W
2. U₁-Q+W
3. U₁ + Q+W
4. U₁ – Q-W

Answer: 1. U₁ + Q-W

Question 11. The work done by an ideal gas at constant temperature is 10 J. The amount of heat gained in this process is

1. 10Cal
2. 2.38 cal
3. Zero
4. Data insufficient

Answer: 2. 2.38 cal

Question 12. The work done by an ideal gas at constant pressure is 10 J. The amount of heat gained in this process is

1. 10cal
2. 2.38 cal
3. zero
4. Data insufficient

Answer: 4. Data insufficient

Question 13. If the internal energy U and the work W are expressed in unit of J and the heat is expressed in unit of cal, the first law of thermodynamics will be [here J = Joule’s equivalent]

1. dQ = dU+\(\frac{dW}{J}\)
2. dQ = dU+JdW
3. JdQ = dU+dW
4. \(\frac{dQ}{J}\)

Answer: 3. JdQ = dU+dW

Question 14. C_v = 5/2, for 1 mol of any diatomic ideal ga  of the ratio of the two specific heats is \(\left[\frac{C_p}{C_v}=\gamma\right]\) of the gas is

1. \(\frac{4}{3}\)
2. \(\frac{5}{3}\)
3. \(\frac{7}{3}\)
4. \(\frac{7}{5}\)

Answer: 4. \(\frac{7}{5}\)

Question 15. If R = 2 cal · mol^-1 · °C^-1 and hydrogen is assumed to be an ideal gas, specific heat1 of that gas at constant pressure will be

1. 7 cal g °C^-1
2. 5 cal g °C^-1
3. 3.5 cal · g^{-1 ·} °C^-1
4. 1.25 cal · g^-1 · °C^-1

Answer: 3. 3.5 cal · g^-1 · °C^-1

Question 16. Work done becomes zero

1. At constant pressure
2. At constant volume
3. In isothermal process
4. In adiabatic process

Answer: 2. At constant volume

Question 17. The change in internal energy of an ideal gas becomes zero

1. At constant pressure
2. At constant volume
3. In isothermal process
4. In adiabatic process

Answer: 3. In isothermal process

Question 18. The process in which changes in pressure, volume and temperature occur simultaneously is

1. Isobaric
2. Isochoric
3. Isothermal
4. Adiabatic

Answer: 4. Adiabatic

Question 19. It is observed by comparing the specific heats of all solid, liquid, and gaseous substances that

1. Specific heat of water is the highest
2. Specific heats of hydrogen and helium are higher than that of water
3. All gases have specific heat higher than that of water
4. All liquid and gases have specific heats higher than that of water

Answer: 2. Specific heats of hydrogen and helium are higher than that of water

Question 20. In an adiabatic expansion, the change in internal energy of 10 mol of a gas is 100 J. What is the amount of work done by the gas?

1. -100 J
2. 100 J
3. 1000 J
4. -1000 J

Answer: 2. 100 J

Question 21. Which of the following relations does an ideal gas follow in an adiabatic process?

1. pV = RT
2. pV^γ = constant
3. \(\left(p+\frac{a}{V^2}\right)(V-b)=R T\)
4. \(p V^{\gamma-1}\)= constant

Answer: 2. pV^γ = constant

Question 22. The slope of an isothermal curve is always

1. Same as that of an adiabatic curve
2. Greater than that of an adiabatic curve
3. Less than that of an adiabatic curve
4. Not derivable

Answer: 3. Less than that of an adiabatic curve

Question 23. ‘Heat cannot transmit from a body at lower temperature to a body at higher temperature on its own’— which law is this statement derived from?

1. First law of thermodynamics
2. Second law of thermodynamics
3. Law of conservation of momentum
4. Law of conservation of mass

Answer: 2. Second law of thermodynamics

Question 24. A system can go from state A to state B in two different processes 1 and 2. If the change in internal energy in the two cases are ΔU₁ and ΔU₂, respectively, then

1. \(\Delta U_1<\Delta U_2\)
2. \(\Delta U_1>\Delta U_2\)
3. \(\Delta U_1=\Delta U_2\)
4. The relation between \(\Delta U_1 and \Delta U_1\) is uncertain

Answer: 3. \(\Delta U_1=\Delta U_2\)

Question 25. In a given process of an ideal gas, dW = 0 and dQ < 0. Then for the gas

1. The temperature will decrease
2. The volume will increase
3. The pressure will remain constant
4. The temperature will increase

Answer: 1. The temperature will decrease

Question 26. 5.6 L of helium gas at STP is adiabatically compressed to 0.7 L. Taking the initial temperature to be T₁, the work done in the process is

1. \(\frac{9}{8} R T_1\)
2. \(\frac{3}{2} R T_1\)
3. \(\frac{15}{8} R T_1\)
4. \(\frac{9}{2} R T_1\)

Answer: 1. \(\frac{9}{8} R T_1\)

Question 27. During the process, shown work done by the system

1. Continuously increases
2. Continuously decreases
3. First increases then decreases
4. First decreases then increases

Answer: 1. Continuously increases

Question 28. When a system is taken from the state i to the state f along the path if, it is found that Q = 50 cal and w= 20 cal. Along the path ibf, Q = 36 cal. W along the path is

1. 6 cal
2. 16 cal
3. 66 cal
4. 14 cal

Answer: 1. 6 cal

Question 29. A Carnot engine, having an efficiency of \(\eta=\frac{1}{10}\) as heat engine is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is

1. 99 J
2. 90 J
3. 1J
4. 100 J

Answer: 2. 90 J

Question 30. The efficiency of a Carnot heat engine working between temperatures 127°C and 27°C is

1. \(\frac{27}{127}\)
2. \(\frac{100}{127}\)
3. \(\frac{300}{400}\)
4. \(\frac{100}{400}\)

Answer: 4. \(\frac{100}{400}\)

Question 31. The efficiency of an ideal heat engine is

1. 0%
2. 50%
3. 100%
4. None

Answer: 3. 100%

Question 32. Coefficient of performance of a machine is

1. \(\frac{\text { output }}{\text { input }}\)
2. \(\frac{\text { input }}{\text { output }}\)
3. \(\frac{0}{\text { input }}\)
4. None

Answer: 1. \(\frac{\text { output }}{\text { input }}\)

Question 33. Even Carnot engine cannot give 100% efficiency, because we cannot

1. Prevent radiation
2. Find ideal sources
3. Reach absolute zero temperature
4. Eliminate friction

Answer: 3. Reach absolute zero temperature

In this type of question, more than one option are correct.

Question 34. C_v and C_p denote the molar-specific heat capacities of a gas at constant volume and constant pressure, respectively then,

1. (C_p– C_v) larger for A diatomic ideal gas than for a monatomic ideal gas
2. (C_p + C_v) is larger for a diatomic ideal gas than for a monatomic ideal gas
3. C_p/C_v is a target for a diatomic ideal gas than for a monatomic ideal gas
4. C_p x C_v is larger for a diatomic ideal gas than for a monatomic, ideal gas

Answer:

2. (C_p + C_v) is larger for a diatomic ideal gas than for a monatomic ideal gas

4. C_p x C_v is larger for a diatomic ideal gas than for a monatomic, ideal gas

Question 35. Shows the p- V plot of an ideal gas taken through a cycle ABCDA. Part ABC is a semicircle and CDA is half of an ellipse. Then

1. The process during the path A → B is isothermal
2. Heat flows out of the gas during the path B → C → D
3. Work done during the path A → B → C in zero
4. Positive work is done by the gas in the cycle ABCDA

Answer:

1. The process during the path A → B is isothermal

2. Heat flows out of the gas during the path B → C→ D

Question 36. 1 mol of an ideal gas in initial state A undergoes a cyclic process ABCA, as shown. Its pressure at A is p₀. Choose the correct options from the following

1. Internal energies at a and b are the same
2. Work done by the gas in process ab is p₀v₀ ln 4
3. Pressure at C is \(\frac{p_0}{4}\)
4. Temperature at C is \(\frac{t_0}{4}\)

Answer:

1. Internal energies at a and b are the same

3. Pressure at c is \(\frac{p_0}{4}\)

Question 37. In the cyclic process shown, ΔU₁ and ΔU₂ represent the change in internal energy in processes A and B, respectively. If ΔQ is the net heat given to the system in the process and ΔW is the work done by the system in the process. then

1. \(\Delta U_1+\Delta U_2=0\)
2. \(\Delta U_1-\Delta U_2=0\)
3. \(\Delta Q-\Delta W=0\)
4. \(\Delta Q+\Delta W=0\)

Answer:

1. \(\Delta U_1+\Delta U_2=0\)

3. \(\Delta Q-\Delta W=0\)

Question 38. Shows the pV diagrams for a Carnot cycle. In this diagram

1. Curve AB represents the isothermal process and BC adiabatic process
2. Curve AB represents the adiabatic process and BC isothermal process
3. Curve CD represents the isothermal process and DA adiabatic process
4. Curve CD represents the adiabatic process and DA isothermal process

Answer:

2. Curve AB represents the adiabatic process and BC isothermal process

4. Curve CD represents the adiabatic process and DA isothermal process