Question

An isolated box, equally partitioned contains two ideal gases $A$ and $B$ as shown. When the partition is removed, the gases mix. The changes in enthalpy $\left(\Delta H\right)$ and entropy $\left(\Delta S\right)$ in the process, respectively, are:

• A. zero, positive
• B. zero, negative
• C. positive, zero
• D. negative, zero

Answer 1

The correct option is A zero, positive

Two ideal gases are present at same condition of temperature, volume and pressure.
When the partition is removed, during mixing, the change in enthalpy
$\left(\Delta H\right)$ is zero.
Since on mixing, the randomness increases, the entropy increases on mixing and entropy change is positive.
$\Delta S>0$