First and Second Laws of Thermodynamics NEET Questions

Physics - Thermodynamics

First and Second Laws of Thermodynamics MCQ Questions


13.
An electric heater supplies heat to a system at 100 W. The system performs work at 75 J/s. At what rate is the internal energy increasing? (NCERT Exercise 11.7)
A.
75 W
B.
175 W
C.
25 W
D.
100 W
😑 View Answer Rough Work Error
ANSWER :
C. 25 W
14.
In changing state of gas adiabatically from A to B, work done ON the system = 22.3 J. The gas is then taken from A to B via a process where net heat absorbed = 9.35 cal. Net work done by system in the latter process is: (NCERT Exercise 11.5, 1 cal = 4.19 J)
A.
16.9 J
B.
22.3 J
C.
60.5 J
D.
12.0 J
😑 View Answer Rough Work Error
ANSWER :
A. 16.9 J
15.
The work done by a gas against constant pressure P when its volume changes by ΔV is:
A.
ΔW = PΔV
B.
ΔW = P²ΔV
C.
ΔW = ΔV/P
D.
ΔW = P/ΔV
😑 View Answer Rough Work Error
ANSWER :
A. ΔW = PΔV
16.
For 1 g of water converting from liquid to vapour (latent heat = 2256 J/g; ΔW = P(V_g - V_l) = 169.2 J at 1 atm), the change in internal energy ΔU is: (NCERT application of First Law)
A.
2086.8 J
B.
169.2 J
C.
2256 J
D.
2425.2 J
😑 View Answer Rough Work Error
ANSWER :
A. 2086.8 J
17.
For a cyclic process (system returns to initial state), the First Law implies:
A.
ΔU = ΔQ always
B.
ΔW = 0
C.
ΔQ = 0
D.
ΔU = 0, so total heat absorbed equals total work done by the system (ΔQ = ΔW)
😑 View Answer Rough Work Error
ANSWER :
D. ΔU = 0, so total heat absorbed equals total work done by the system (ΔQ = ΔW)
18.
In the First Law, ΔQ − ΔW = ΔU. Although ΔQ and ΔW individually depend on the path, the combination ΔQ − ΔW is:
A.
Path-dependent like ΔQ and ΔW individually
B.
Path-independent — equals ΔU which depends only on initial and final states
C.
Always positive
D.
Always zero
😑 View Answer Rough Work Error
ANSWER :
B. Path-independent — equals ΔU which depends only on initial and final states