Question

A perfect gas goes from state $A$ to another state $B$ by absorbing $8\times {10}^5\text{J}$ of heat and doing $6.5\times {10}^5\text{J}$ of external work. The change in internal energy will be

• A. $1450\text{kJ}$
• B. $150\text{kJ}$
• C. $15\text{kJ}$
• D. $145\text{kJ}$

Answer 1

The correct option is B $150\text{kJ}$

Using,
$\Delta Q=\Delta U+\Delta W$
$\Rightarrow \Delta U=\Delta Q-\Delta W$
$=1.5\times {10}^5\text{J}=150\text{kJ}$