CBSE Class 11 Physics – MCQ and Online Tests – Unit 12 – Thermodynamics
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CBSE Class 11 Physics – MCQ and Online Tests – Unit 12 – Thermodynamics
Question 1.
Which of the following parameters dose not characterize the thermodynamic state of matter?
(a) work
(b) volume
(c) pressure
(d) Temperature
Answer
Answer: (a) work
Question 2.
The translational kinetic energy of gas molecules at temperature T for one mole of a gas is
(a) (3/2) RT
(b) (9/2) RT
(c) (1/3) RT
(d) (5/2) RT
Answer
Answer: (a) (3/2) RT
Question 3.
An engine has an efficiency of 1/6. When the temperature of sink is reduced by 62°C, its efficiency is doubled. Temperature of the source is:
(a) 124°C
(b) 37°C
(c) 62°C
(d) 99°C
Answer
Answer: (d) 99°C
Question 4.
At a given volume and temperature, the pressure of a gas
(a) varies inversely as its mass
(b) varies inversely as the square of its mass
(c) varies linearly as its mass
(d) is independent of its mass
Answer
Answer: (c) varies linearly as its mass
Question 5.
Directions: The following question has four choices out of which ONLY ONE is correct.
In a thermodynamic process, pressure of a fixed mass of the gas is changed in such a manner that the gas molecules give out 30 J of heat. Also, 10 J of work is done on the gas. If the internal energy of the gas was 40 J, what will be the final internal energy?
(a) 20 J
(b) -20 J
(c) 80 J
(d) zero
Answer
Answer: (a) 20 J
Question 6.
The translational kinetic energy of gas molecules at temperature T for one mole of a gas is
(a) (3/2) RT
(b) (9/2) RT
(c) (1/3) RT
(d) (5/2) RT
Answer
Answer: (a) (3/2) RT
Question 7.
Which of the following parameters dose not characterize the thermodynamic state of matter?
(a) work
(b) volume
(c) pressure
(d) Temperature
Answer
Answer: (a) work
Question 8.
Directions: The following question has four choices out of which ONLY ONE is correct.
A Carnots engine works as a refrigerator between 250 K and 300 K. If it receives 750 calories of heat from the reservoir at the lower temperature, the amount of heat rejected at the higher temperature is __________.
(a) 900 cal
(b) 625 cal
(c) 750 cal
(d) 1000 cal
Answer
Answer: (a) 900 cal
Question 9.
The temperatures of inside and outside of a refrigerator are 273 K and 303 K respectively. Assuming, that the refrigerator cycle is reversible, for every joule of work done, the heat delivered to the surrounding will be nearly:
(a) 10 J
(b) 20 J
(c) 30 J
(d) 50 J
Answer
Answer: (c) 30 J
Question 10.
Directions: The following question has four choices out of which ONLY ONE is correct.
In a thermodynamic process, pressure of a fixed mass of the gas is changed in such a manner that the gas molecules give out 30 J of heat. Also, 10 J of work is done on the gas. If the internal energy of the gas was 40 J, what will be the final internal energy?
(a) 20 J
(b) -20 J
(c) 80 J
(d) zero
Answer
Answer: (a) 20 J
Question 11.
A Carnot engine whose sink is at 300 K has an efficiency of 40%. By how much should the temperature of source be increased, so as to increase its efficiency by 50% of original efficiency?
(a) 275 K
(b) 325 K
(c) 250 K
(d) 380 K
Answer
Answer: (c) 250 K
Question 12.
For a diatomic gas change in internal energy for a unit change in temperature for constant pressure and constant volume is U1 and U2 respectively. What is the ratio of U1 and U2?
(a) 5 : 3
(b) 3 : 5
(c) 1 : 1
(d) 5 : 7
Answer
Answer: (c) 1 : 1
Question 13.
Directions: The following question has four choices out of which ONLY ONE is correct.
A thermodynamical system is changed from state (P1, V1) to (P², V²) by two different processes, the quantity which will remain same is:
(a) ?Q
(b) ?W
(c) ?Q + ?W
(d) ?Q – ?W
Answer
Answer: (d) ?Q – ?W
Question 14.
The temperatures of inside and outside of a refrigerator are 273 K and 303 K respectively. Assuming, that the refrigerator cycle is reversible, for every joule of work done, the heat delivered to the surrounding will be nearly:
(a) 10 J
(b) 20 J
(c) 30 J
(d) 50 J
Answer
Answer: (c) 30 J
Question 15.
During an adiabatic process, the pressure of a gas is found to be proportional to the cube of its absolute temperature. The ratio Cp/Cv for the gas is
(a) 2
(b) 3/2
(c) 4/3
(d) 5/3
Answer
Answer: (b) 3/2
Question 16.
Directions: The following question has four choices out of which ONLY ONE is correct.
A thermodynamical system is changed from state (P1, V1) to (P², V²) by two different processes, the quantity which will remain same is:
(a) ?Q
(b) ?W
(c) ?Q + ?W
(d) ?Q – ?W
Answer
Answer: (d) ?Q – ?W
Question 17.
Heat cannot by itself flow from a body at lower temperature to a body at higher temperature is a statement as a conseqence of
(a) conservation of mass
(b) conservation of momentum
(c) first law of thermodynamics
(d) second law of thermodynamics
Answer
Answer: (d) second law of thermodynamics
Question 18.
Which of the following statements is correct for any thermodynamic system?
(a) The internal energy changes in all processes.
(b) Internal energy and entropy are state functions.
(c) The change in entropy can never be zero.
(d) The work done in an adiabatic process is always zero.
Answer
Answer: (b) Internal energy and entropy are state functions.
Question 19.
A black body at a temperature of 227°C radiates heat at the rate of 20 cal m-2s-1. When its temperature rises to 727°C, the heat radiated will be
(a) 40 units
(b) 160 units
(c) 320 units
(d) 640 units
Answer
Answer: (c) 320 units
Question 20.
Directions: The following question has four choices out of which ONLY ONE is correct.
Which of the following is incorrect regarding the first law of thermodynamics? A. It is not applicable to any cyclic process B. It is a restatement of the principle of conservation of energy C. It introduces the concept of the internal energy D. It introduces the concept of the entropy
(a) A and D
(b) B and C
(c) C and A
(d) A and B
Answer
Answer: (a) A and D
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