A gas is compressed at a constant pressure of `50N//m^(2)` from a volume `10m^(3)` to a volume of `4m^(3)`. 100J of heat is added to the gas then its internal energy is

Options

A. increased by 200 J
B. increased by 400 J
C. decreased by 200 J
D. increased by 100 J

Answer

B

Explanation

When we compress the gas, the work done on the gas is negative.
`therefore` Work done = dW = PdV
`=50xx(-6)=-300J`
`thereforedQ=dU+dW`
`thereforedU=dQ-dW=dQ-PdV`
`thereforedU=100-(-300)=400J`