Question

An insulated container is divided into two equal portions. One portion contains an ideal gas at pressure $P$ and temperature $T$. The other portion is a perfect vacuum, if a hole is opened between two portion then

• A. Temperature remains constant
• B. Temperature increases
• C. Temperature decreases
• D. Temperature is initially constant and then increases

Answer 1

The correct option is A Temperature remains constant

Since container is insulated
$\therefore q$ is $0$. Expansion is free thus $w=0$
$\therefore$ From $1^{st}$ law of thermodynamics
$\Delta U=q+W=0$ as $q=0,W=0$ & $T$ is function of $\Delta U$ thus temperature remains constant.