CBSE Class 11 Physics Thermodynamic MCQs Set B

Question: Which of the following relations does not give the equation of an adiabatic process, where terms have their usual meaning?
a) P1 - g Tg = constant
b) PVg = constant
c) TV g - 1 = constant
d) PgT1 - g = constant
Answer: d

Question: During an isothermal expansion, a confined ideal gas does -150 J of work against its surroundings.
This implies that
a) 150 J of heat has been removed from the gas
b) 300 J of heat has been added to the gas
c) no heat is transferred because the process is isothermal
d) 150 J of heat has been added to the gas.
Answer: d

Question: First law of thermodynamics is consequence of conservation of
a) work
b) energy
c) heat
d) all of the options
Answer: b

Question: We consider a thermodynamic system. If DU represents the increase in its internal energy and W the work done by the system, which of the following statements is true?
a) DU = -W in an isothermal process
b) DU = W in an isothermal process
c) DU = -W in an adiabatic process
d) DU = W in an adiabatic process
Answer: c

Question: An ideal gas, undergoing adiabatic change, has which of the following pressure temperature relationship?
a) PgT1-g = constant
b) P1-g Tg = constant
c) Pg-1 Tg = constant
d) PgTg-1 = constant
Answer: b

Question: If cp and cv denote the specific heats per unit mass of an ideal gas of molecular weight M, then
a) c_p - c_v = R/M²
b) c_p - c_v = R
c) c_p - c_v = R/M
d) c_p - c_v = MR
Answer: c

Question: Absolute zero is obtained from
a) P-V graph
b) P - 1/V graph
c) P-T graph
d) V-T graph
Answer: c

Question: If the ratio of specific heat of a gas at constant pressure to that at constant volume is g, the change in internal energy of a mass of gas, when the volume changes from V to 2V at constant pressure P, is
a) PV /(γ - 1)
b) PV
c) R /(γ - 1)
d) γPV /(γ - 1)
Answer: a

Question: If DU and DW represent the increase in internal energy and work done by the system respectively in a thermodynamical process, which of the following is true?
a) DU = - DW, in an adiabatic process
b) DU = DW, in an isothermal process
c) DU = DW, in an adiabatic process
d) DU = -DW, in an isothermal process
Answer: a

Question: A cylinder contains hydrogen gas at pressure of 249 kPa and temperature 27°C. Its density is (R = 8.3 J mol^-1 K^-1)
a) 0.5 kg/m³
b) 0.2 kg/m³
c) 0.1 kg/m³
d) 0.02 kg/m³
Answer: b

Question: If Q, E and W denote respectively the heat added,change in internal energy and the work done in a closed cyclic process, then
a) E = 0
b) Q = 0
c) W = 0
d) Q = W = 0
Answer: a

Question: Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains an ideal gas at standard temperature and pressure.B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. The process is
a) isothermal
b) adiabatic
c) isochoric
d) isobaric
Answer: b

Question: 110 joule of heat is added to a gaseous system whose internal energy is 40 J, then the amount of external work done is
a) 150 J
b) 70 J
c) 110 J
d) 40 J
Answer: b

Question: One mole of an ideal gas at an initial temperature of T K does 6R joules of work adiabatically. If the ratio of specific heats of this gas at constant pressure and at constant volume is 5/3, the final temperature of gas will be
a) (T - 4) K
b) (T + 2.4) K
c) (T - 2.4) K
d) (T + 4) K
Answer: a

Question: Three moles of an ideal gas kept at a constant temperature at 300 K are compressed from a volume of 4 litre to 1 litre.The work done in the process is
a) - 10368 J
b) -110368 J
c) 12000 J
d) 120368 J
Answer: a

Question: A monatomic gas at a pressure P, having a volume V expands isothermally to a volume 2V and then adiabatically to a volume 16V. The final pressure of the gas is (Take g = 5/3)
a) 64P
b) 32P
c) P/64
d) 16P
Answer: d

Question: Unit mass of a liquid with volume V1 is completely changed into a gas of volume V₂ at a constant external pressure P and temperature T.If the latent heat of evaporation for the given mass is L, then the increase in the internal energy of the system is
a) Zero
b) P(V₂ - V₁)
c) L - P(V₂ - V₁)
d) L
Answer: c

Question: During an adiabatic process, the pressure of a gas is found to be proportional to the cube of its temperature. The ratio of Cp/Cv for the gas is
a) 5/3
b) 3/2
c) 4/3
d) 2
Answer: b

Question: A sample of 0.1 g of water at 100°C and normal pressure (1.013 × 10⁵ N m^-2) requires 54 cal of heat energy to convert to steam at 100°C. If the volume of the steam produced is 167.1 cc, the change in internal energy of the sample, is
a) 104.3 J
b) 208.7 J
c) 42.2 J
d) 84.5 J
Answer: b

Question: A monatomic gas at pressure P₁ and volume V₁ is compressed adiabatically to 1/8th of its original volume. What is the final pressure of the gas?
a) 64P₁
b) P₁
c) 16P₁
d) 32P₁
Answer: d

Question: In an adiabatic change, the pressure and temperature of a monatomic gas are related as P ∝ TC, where C equals
a) 3/5
b) 5/3
c) 2/5
d) 5/2
Answer: d

Question: In an adiabatic process, the pressure is increased by 2/3 % If γ = 3/2 then the volume decreases by nearly
a) 4/9 %
b) 2/3 %
c) 1 %
d) 9/4 %
Answer: a

Question: A mass of diatomic gas (g = 1.4) at a pressure of 2 atmospheres is compressed adiabatically so that its temperature rises from 27°C to 927°C. The pressure of the gas in the final state is
a) 8 atm
b) 28 atm
c) 68.7 atm
d) 256 atm
Answer: d

Question: The internal energy change in a system that has absorbed 2 kcal of heat and done 500 J of work is
a) 6400 J
b) 5400 J
c) 7900 J
d) 8900 J
Answer: c

Question: A sample of gas expands from volume V1 to V2. The amount of work done by the gas is greatest, when the expansion is
a) adiabatic
b) equal in all cases
c) isothermal
d) isobaric.
Answer: d

Question: A diatomic gas initially at 18°C is compressed adiabatically to one eighth of its original volume.The temperature after compression will be
a) 395.4°C
b) 144°C
c) 18°C
d) 887.4°C
Answer: a

Question: An ideal gas is compressed to half its initial volume by means of several processes. Which of the process results in the maximum work done on the gas?
a) Isochoric
b) Isothermal
c) Adiabatic
d) Isobaric
Answer: c

Question: A gas is compressed isothermally to half its initial volume. The same gas is compressed separately through an adiabatic process until its volume is again reduced to half. Then
a) Compressing the gas isothermally or adiabatically will require the same amount of work.
b) Which of the case (whether compression through isothermal or through adiabatic process) requires more work will depend upon the atomicity of the gas.
c) Compressing the gas isothermally will require more work to be done.
d) Compressing the gas through adiabatic process will require more work to be done.
Answer: d

Question: A thermodynamic system goes from states (i) P₁, V to 2P₁, V (ii) P, V₁ to P, 2V₁. Then work done in the two cases is
a) zero, zero
b) zero, PV₁
c) PV₁, zero
d) PV₁, P₁V₁
Answer: b

Question: When 1 kg of ice at 0°C melts to water at 0°C, the resulting change in its entropy, taking latent heat of ice to be 80 cal/°C, is
a) 273 cal/K
b) 8 × 10⁴ cal/K
c) 80 cal/K
d) 293 cal/K
Answer: d

Question: In which of the following processes, heat is neither absorbed nor released by a system?
a) isochoric
b) isothermal
c) adiabatic
d) isobaric
Answer: c

Question: Which of the following is not thermodynamical function ?
a) Enthalpy
b) Work done
c) Gibb’s energy
d) Internal energy
Answer: b

Question: During an adiabatic process an object does 100J of work and its temperature decreases by 5K. During another process it does 25J of work and its temperature decreases by 5K. Its heat capacity for 2nd process is
a) 20 J/K
b) 24 J/K
c) 15 J/K
d) 100 J/K
Answer: c

Question: One mole of an ideal monatomic gas undergoes a process described by the equation PV3 = constant.The heat capacity of the gas during this process is
a) 3 /2R
b) 5/2R
c) 2R
d) R
Answer: d

Question: An ideal gas heat engine operates in Carnot cycle between 227°C and 127°C. It absorbs 6 × 10⁴ cals of heat at higher temperature. Amount of heat converted to work is
a) 4.8 × 10⁴ cal
b) 6 × 10⁴ cal
c) 2.4 × 10⁴ cal
d) 1.2 × 10⁴ cal
Answer: d

Question: One mole of an ideal gas requires 207 J heat to rise the temperature by 10 K when heated at constant pressure. If the same gas is heated at constant volume to raise the temperature by the same 10 K, the heat required is (Given the gas constant R = 8.3 J/mole K)
a) 198.7 J
b) 29 J
c) 215.3 J
d) 124 J
Answer: d

Question: The specific heat capacity of a monoatomic gas for the process TV₂ = constant is (where R is gas constant)
a) R
b) 2 R
c) R/3
d) R/4
Answer: a

Question: One mole of an ideal gas at an initial temperature of T K does 6R joule of work adiabatically. If the ratio of specific heats of this gas at constant pressure and at constant volume is 5/3, the final temperature of gas will be
a) (T + 2.4) K
b) (T - 2.4) K
c) (T + 4) K
d) (T - 4) K
Answer: d

Question: An ideal gas at 27°C is compressed adiabatically to 8/27 of its original volume. The rise in temperature is (Take g = 5/3)
a) 275 K
b) 375 K
c) 475 K
d) 175 K
Answer: b