Thermodynamics - Online Test

Q1. Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. What is the change in internal energy of the gas?
Answer : Option B
Explaination / Solution:

Internal energy depends on temperature and temperature remains constant because system is thermally insulated. so that change in internal energy will be zero.

Q2. Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. What is the change in the temperature of the gas?
Answer : Option C
Explaination / Solution:

Temperature remains constant because system is thermally insulated. so that change in temperature will be zero.

Q3. Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. Do the intermediate states of the system (before settling to the final equilibrium state) lie on its P-V-T surface?
Answer : Option C
Explaination / Solution:

Pressure and volume will be changed.

Q4. A steam engine delivers 5.4 J of work per minute and services  of heat per minute from its boiler. What is the efficiency of the engine? How much heat is wasted per minute?
Answer : Option C
Explaination / Solution:


Heat Wasted = 


Q5. An electric heater supplies heat to a system at a rate of 100W. If the system performs work at the rate of 75 joules per second, at what rate is the internal energy increasing?
Answer : Option C
Explaination / Solution:

ΔQ=ΔU+WΔU=10075=25Watt
Q6. A thermodynamic system is taken from an original state to an intermediate state by the linear process shown in Figure. Its volume is then reduced to the original value from E to F by an isobaric process. Calculate the total work done by the gas from D to E to F

Answer : Option B
Explaination / Solution:

work done by the gas is equal to area under P-V curve

Q7.

A 1.0-mol sample of an ideal gas is kept at 0.0C during an expansion from 3.0 L to 10.0 L. How much energy transfer by heat occurs with the surroundings in this process?


Answer : Option C
Explaination / Solution:

in isothermal process  

hence 



 


Q8. A refrigerator is to maintain eatables kept inside at 9 C. If room temperature is 36C, calculate the coefficient of performance.
Answer : Option D
Explaination / Solution:

K=TLTHTL=282309282=10.4
Q9.

A 1.0-mol sample of an ideal gas is kept at 0.0C during an expansion from 3.0 L to 10.0 L. How much work is done by the gas during the expansion?


Answer : Option B
Explaination / Solution:

In isothermal process


Q10. A 1.0-mol sample of an ideal gas is kept at 0.0C during an expansion from 3.0 L to 10.0 L. If the gas is returned to the original volume by means of an isobaric process, how much work is done by the gas?
Answer : Option A
Explaination / Solution: