# NEET Physics Thermodynamics Questions Solved

P-V diagram of a cyclic process ABCA is as shown in figure. Choose the correct statement

(1) $\Delta {Q}_{A\to B}$ = negative

(2) $\Delta {U}_{B\to C}$ = positive

(3) $\Delta {W}_{CAB}$ = negative

(4) All of these

(4) During process A to B, pressure and volume both are decreasing. Therefore, temperature and hence, internal energy of the gas will decrease (TPV) or $\Delta {U}_{A\to B}=$ negative. Further $\Delta {W}_{A\to B}$ is also negative as the volume of the gas is decreasing. Thus $\Delta {Q}_{A\to B}$ is negative.

In process B to C pressure of the gas is constant while volume is increasing. Hence temperature should increase or $\Delta {U}_{B\to C}$ = positive. During C to A volume is constant while pressure is increasing. Therefore, temperature and hence, internal energy of the gas should increase or $\Delta {U}_{C\to A}$ = positive. During process CAB volume of the gas is decreasing. Hence, work done by the gas is negative.

Difficulty Level:

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