NEET Physics Specific Heat Capacity and Thermodynamical Processes MCQs Set 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.  In a thermodynamic process, pressure of a fixed mass of gas is changed in such a manner that the gas molecules gives out 30 joules of heat and 10 J of work is done on the gas. If the initial internal energy of the gas was 40J, then final internal energy will be
(a) 20 J
(b) –20 J
(c) 80 J
(d) zero

Answer: A

Question. Calculate the work done when 1 mole of a perfect gas is compressed adiabatically. The initial pressure and volume of the gas are 105 N/m2 and 6 litre respectively. The final volume of the gas is 2 litres. Molar specific heat of the gas at constant volume is 3R/2. [Given (3)5/3 = 6.19]
(a) –957 J
(b) +957 J
(c) – 805 J
(d) + 805 J

Answer: A

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) L – P(V₂ – V₁)
(b) Zero
(c) P(V₂ – V₁)
(d) L

Answer: A

Question.  A certain amount of ideal monoatomic gas undergoes, process given by UV^1/2 = C where U is the internal energy of the gas. The molar specific heat of the gas for the process will be
(a) –R/2
(b) 5R/2
(c) 3R
(d) R/2

Answer: A

Question.  When the state of a gas adiabatically changed from an equilibrium state A to another equilibrium state B an amount of work done on the stystem is 35 J. If the gas is taken from state A to B via process in which the net heat absorbed by the system is 12 cal, then the net work done by the system is (1 cal = 4.19 J
(a) 15.4 J
(b) 13.2 J
(c) 12.6 J
(d) 16.8 J

Answer: A

Question.  Two cylinders A and B fitted with pistons contain equal amounts of an ideal diatomic gas at 300 K. The piston of A is free to move while that of B is held fixed. The same amount of heat is given to the gas in each cylinder. If the rise in temperature of the gas in A is 30 K, then the rise in temperature of the gas in B is
(a) 42 K
(b) 50 K
(c) 18 K
(d) 30 K

Answer: A

Question.  Which of the following processes is reversible?
(a) None of these
(b) Electrical heating of a nichrome wire
(c) Isothermal compression
(d) Transfer of heat by conduction

Answer: A

Question. Assertion : When a bottle of cold carbonated drink is opened a slight fog forms around the opening.
Reason : Adiabatic expansion of the gas causes lowering of temperature and condensation of water vapours.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Both
(d) None of these

Answer: A