Consider the following processes (treat all gases as ideal).
1.The pressure of 1 mol of oxygen gas is allowed to double isothermally.
2.Carbon dioxide is allowed to expand isothermally to 10 times its original volume.
3.The temperature of 1 mol of helium is increased 25°C at constant pressure.
4.Nitrogen gas is compressed isothermally to half its original volume.
5.A glass of water loses 100 J of energy reversibly at 30°C.
Which of these processes lead(s) to a decrease in entropy?
A)1 and 2
B)2
C)3 and 4
D)1,4,and 5
E)1 and 3

Question

Consider the following processes (treat all gases as ideal).
1.The pressure of 1 mol of oxygen gas is allowed to double isothermally.
2.Carbon dioxide is allowed to expand isothermally to 10 times its original volume.
3.The temperature of 1 mol of helium is increased 25°C at constant pressure.
4.Nitrogen gas is compressed isothermally to half its original volume.
5.A glass of water loses 100 J of energy reversibly at 30°C.
Which of these processes lead(s) to a decrease in entropy? 
A)1 and 2
B)2
C)3 and 4
D)1,4,and 5
E)1 and 3

Quizplus · Accepted Answer

Entropy decreases when a system loses energy or when the volume of a gas decreases isothermally. In process 1, the volume decreases as pressure doubles isothermally, leading to a decrease in entropy. In process 4, compressing nitrogen gas to half its volume isothermally also decreases entropy. In process 5, the glass of water losing energy reversibly at a constant temperature results in a decrease in entropy.

Consider the Following Processes (Treat All Gases as Ideal)