Question

An ideal gas is enclosed in a cubical container. The container has a hole in its top face. During the process of heating, at any instant the internal energy of the gas enclosed in the container is $U$, (Neglect the thermal expansion of the container) then the value of $U$

• A. decreases continuously
• B. remains constant
• C. increases continuously
• D. first decreases, then increases

Answer 1

The correct option is B remains constant

As container has a hole at the top pressure remains to be atmospheric.
Neglecting thermal expansion total volume of container remains same.

Internal energy, $U=\frac{f}{2}PV$

$P$ and $V$ both are constant and as degrees of freedom is constant for a particular gas, $U$ will remain constant.