Question

When 1 mole of gas is heated at constant volume. Temperature is raised from $298$ 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)

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