Question

When $1$ mole gas is heated at constant volume, temperature is raised from $298\, K$ to $308\, K$. Heat supplied to the gas is $500\, J$. Then which statement is correct?

• A. $q=W=500\, J,\, \Delta U=0$
• B. $q=\Delta U=500\, J,\, W=0$
• C. $q=W= - 500\, J,\, \Delta U=0$
• D. $\Delta U=0,\,q=W=-500\, J$

Answer 1

Answer: (B)

As we know that $\Delta H=\Delta E +p \Delta V$
When $\Delta V=0$
$\therefore \Delta H=\Delta E$
From first law of thermodynamics
$\Delta U=q +W$
In the given problem, $\Delta H=500\, J$
$-W= -p \Delta V,\, \Delta V=0$
So, $\Delta U=q=500\, J$