Second Law Of Thermodynamics MCQ Level – 2 (Part - 1) - Physics MCQ

Hence, entropy increases or decreases as heat is supplied or removed in reversible manner.
The correct answer is: entropy

From i to a and i to b, change in temperature is same, hence dU remains same for both the processes. But i to a is isochoric process, hence work done is zero.
⇒ heat gained in process a is smaller, hence the entropy change along the pathto state a is smaller than b.
The correct answer is: smaller than b

Efficiency 
Available energy per cycle is = Q₁ – Q₂
 = Area of curve ABC
Q₁ = Total area of curve (ABCD)
⇒ Area of curve is same for both figures, but total area is more for figure 1.
⇒ 
Hence, second figure, has greater efficiency
The correct answer is: Second

dS = 
for constant temperature, dU = 0

and   

The correct answer is: 

if T_L is reduced, η can be increased.
The correct answer is: decreasing the lowest temperature

Kelvin-Plank statement of the second law of thermodynamics states that it is impossible to devise a cyclically operating device, the sole effect of which is to absorb energy in the form of heat from a single thermal reservoir and to deliver an equivalent amount of work.
The correct answer is: conversion of heat into work

For all reversible processes and constitutes part of the second law of thermodynamics, the entropy of the universe remains constant in a reversible process.

Change in entropy



pV = RT


The correct answer is:  

Entropy is a measure of the number of microscopic configurations that a thermodynamic system can have when in a state as specified by some macroscopic variable.
The correct answer is: on the thermodynamic state

When dealing with a system that is not isolated from its surroundings, remember that the increase in entropy described in the second law is that of the system and its surroundings. When a system and its surrounding interact in an irreversible process, the increase in entropy of one is greater than the decrease in entropy of the other. Hence, we conclude that the change in entropy of the universe must be greater than zero for an irreversible process and equal to zero for a reversible process.
The correct answer is: increases