Thermodynamics Question 142

Question: A perfect gas goes from state A to another state B by absorbing 8×105J of heat and doing 6.5×105J of external work. It is now transferred between the same two states in another process in which it absorbs 105J of heat. Then in the second process

[BHU 1997]

Options:

A) Work done on the gas is 0.5×105J

B) Work done by gas is 0.5×105J

C) Work done on gas is 105J

D) Work done by gas is 105J

Show Answer

Answer:

Correct Answer: A

Solution:

In first process using ΔQ=ΔU+ΔW

Therefore 8×105=ΔU+6.5×105

Therefore ΔU=1.5×10J

Since final and initial states are same in both process

So ΔU will be same in both process

For second process using ΔQ=ΔU+ΔW

Therefore 105=1.5×105+ΔW

Therefore ΔW=0.5×105J



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