NEET UG Physics Thermodynamics MCQs

22. One mole of a monoatomic ideal gas is mixed with one mole of a diatomic ideal gas The molas specific heat of the micture at constant volume is ____
(A) 4 R (B) 3 R (C) R (D) 2R

23. One mole of a monoatomic gas is heate at a constant pressure of 1 atmosphere from 0k to 100 k.
If the gas constant R = 8.32 J/mol k the change in internal energy of the gas is approximate ?
(A) 23 J (B) 1.25×10³ J (C) 8.67× 10³ J (D) 46 J

24. A gas mixture consists of 2 mde of oxygen and 4 mole of argon at tempressure T.Neglecting all vibrational modes, the total internal energy of the system is
(A) 11 RT (B) 9 RT (C) 15 RT (D) 4 RT

34. The first law of thermodynamics is concerned with the conservation of
(A) momentum (B) energy (C) mass (D) temperature

35. If heat given to a system is 6 k cal and work done is 6kj. The change in internal energy is _____KJ.
(A) 12.4 (B) 25 (C) 19.1 (D) 0

36. The internal energy change in a system that has absorbed 2 Kcal of heat and done 500J of work is
(A) 7900 J (B) 4400 J (C) 6400 J (D ) 8900 J

37. Which of the following is not a thermodynamical function.
(A) Enthalpy (B) Work done
(C) Gibb's energy (D) Internal energy

38. Which of the following is not a thermodynamic co-ordinate.
(A) R (B) P (C) T (D) V

39. The work of 62-25 KJ is performed in order to compress one kilo mole of gas adiabatically and in this process the temperature of the gas increases by 5⁰C The gas is _______ R = 8-3    ^J/_molk
(A) triatomic (C) monoatomic
(B) diatomic (D) a mixture of monoatomic and diatomic

105. Efficiency of a car not engine is 50%, when temperature of outlet is 500K. in order to increase efficiency up to 60% keeping temperature of intake the same what is temperature of out let.
(A) 200 K (B) 400 K (C) 600 K (D) 800 K

106. A car not engine takes 3×10⁶ cal of heat from a reservoir at 627°C , and gives to a sink at 27°C.
The work done by the engine is
(A) 4.2×10⁶ J (B) 16.8×10⁶ J (C) 8.4×10⁶ J (D) Zero

107. For which combination of working temperatures the efficiency of Car not's engine is highest.
(A) 80 K, 60 K (B) 100 K, 80 K (C) 60 K, 40 K (D) 40 K, 20 K

108. An ideal heat engine working between temperature T₁ and T₂ has an efficiency n. The new efficiency if both the source and sink temperature are doubled, will be
(A) n (B) 2n (C) 3n (D) n/2

109. An ideal refrigerator has a freetes at a temperature of -13°C, The coefficent of perfomance of the engine is 5. The temperature of the air to which heat is rejected will be.
(A) 325°C (B) 39°C (C) 325 K (D) 320°C

110. An engine is supposed to operate between two reservoirs at temperature 727°C and 227°C. The maximum possible efficiency of such an engine is
(A) 3/4
(B) 1/4
(C) 1/2
(D) 1

117. If a heat engine absorbs 50KJ heat from a heat source and has efficiency of 40%, then the heat released by it in heat sink is _____
(A) 40 KJ (B) 30 KJ (C) 20 J (D) 20 KJ

118. The efficiency of heat engine is 30% If it gives 30KJ heat to the heat sink, than it should have absorbed _____ KJ heat from heat source.
(A) 42.8 (B) 39 (C) 29 (D) 9

119. If a heat engine absorbs 2KJ heat from a heat source and release 1.5KJ heat into cold reservoir, then its efficiency is ____
(A) 0.5% (B) 75% (C) 25% (D) 50%

120. If the doors of a refrigerators is kept open, then which of the following is true?
(A) Room is cooled (B) Room is eithers cooled or heated
(C) Room is neither cooled nor heated (D) Room is heated

Assertion-Reason

Instructions :-

Read the assertion and reason carefully to mask the correct option out of the options given below.
(A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(B) If both assertion and reason are true but reason is not be correct explanation of assertion.
(C) If assertion is true but reason is false.
(D) If the assertion and reason both are false.

121. Assertion : The melting point of ice decreases with increase of Pressure
        Reason : Ice contracts on melting.
(A) C (B) B (C) A (D) D

122. Assertion : Fahrenhit is the smallest unit measuring temperature.
        Reason : Fahrenhit was the first temperature scale used for measuring temperature.
(A) A (B) C (C) B (D) D

123. Assertion : A beakes is completely, filled with water at 4°C. It will overlow, both when heated or cooled.
        Reason : These is expansion of water below 4⁰ C
(A) A (B) B (C) C (D) D

124.  Assertion : The total translation kinetic energy of all the molecules of a given mass of an ideal gas is 1-5 times the product of its Pressure and its volume.
         Reason : The molecules of a gas collide with each other and velocities of the molecules change due to the collision
(A) D (B) C (C) A (D) B

125. Assertion : The car not is useful in understanding the perfomance of heat engine
        Reason : The car not cycle provides a way of determining the maximum possible efficiency achivable with reservoirs of given temperatures.
(A) A (B) B (C) C (D) D

(A) A-p, B-s, C-r, D-q (C) A-r, B-p, C-s, D-q
(B) A-s, B-q, C-p, D-r (D) A-q, B-r, C-q, D-p

Comprehehsion Type

In a containes of negligible heat capacity, 200g ice at 0°C and 100g steam at 100°C are added to  200g of water that has temperature 55C.Assume no heat is lost to the surroundings and the pressure in the container is constant 1 atm. 

128. What is the final temperature the System ?
(A) 72°C (B) 48°C (C) 100°C (D) 94°C

129. At the final temperature, mass of the toal water present in the system is
(A) 493.6g (B) 483.3g (C) 472.6 g (D) 500 g

130. Amount of the Sm left in the system, is equal to
(A) 16-7 g (B) 8-4 g (C) 12 g (D) 0 g