Question

A gas is at $10Pa$ pressure with a volume $8m^3$. When $100J$ of heat is supplied to the gas, it expands to $10m^3$ at constant pressure. The change in its internal energy is :

• A. $80J$
• B. $-80J$
• C. $20J$
• D. $-20J$

Answer 1

The correct option is A $80J$

Given $P=10Pa$
Work done in an isobaric process: $P(V_2-V_1)=P(10-8)=10\times 2=20Joule$
$\Delta U=Q-W=(100-20)=80Joule$