# Applications of Entropy Principle - MCQs with Answers

Q1. How are the entropy increase of the universe during the irreversible process and its irreversibility are related?

a. higher the entropy increase of the universe, lower will be the irreversibility
b. higher the entropy increase of the universe, higher will be the irreversibility
c. change in entropy increase of the universe does not change the irreversibility
d. none of the above.

ANSWER: b. higher the entropy increase of the universe, higher will be the irreversibility

Q2. When heat is transferred from body A which is at temperature T1 to body B which at temperature T2 and there is no heat loss to the surrounding, what will be the change in entropy (dS) of the universe? (Given T1 > T2)

a. dS will remain constant
b. dS will be positive
c. dS will be negative
d. dS will either positive or negative

ANSWER: b. dS will be positive

Q3. How is the final temperature (Tf) of the two bodies given, when these bodies, having same heat capacity and initially at temperatures T1 and T2 (T1>T2) are brought together in thermal contact, without delivering any work?

a. Tf = (T1 – T2)
b. Tf = (T1 – T2) / 2
c. Tf = (T1 + T2) / 2
d. Tf = √T1 T2

ANSWER: c. Tf = (T1 + T2) / 2

Q4. Two bodies, initially at temperatures T1 and T2 (T1>T2) have same heat capacity. Suppose a heat engine is operated between these two bodies delivering work. What will be the final temperature (Tf) of the two bodies when after that temperature heat engine will stop working with giving maximum work?

a. Tf = (T1 – T2)
b. Tf = (T1 – T2) / 2
c. Tf = (T1 + T2) / 2
d. Tf = √T1 T2

Q5. A body is at a temperature T1 with certain heat capacity and a heat engine is operated between the body and a thermal heat reservoir at temperature (T0). What will be the final temperature of the body when heat engine will stop working?

a. T1
b. T0
c. (T1 + T0) / 2
d. Tf = √T1 T2

Q6. An electric current I is passing through a resistor in contact with a reservoir. The internal energy of the resistor is constant. Heat generated is absorbed by surrounding at temperature T0. What will be the effect on entropy of the universe?

a. Entropy of the universe is always constant
b. The process increases the the entropy of the universe
c. The process decreases the the entropy of the universe
d. cannot say