Question

When vapour condenses into a liquid:

• A. It absorbs heat
• B. It liberates heat
• C. Its temperature increases
• D. Its temperature decreases

Answer 1

The correct option is B It liberates heat

During the phase transition, heat is liberated if the vapour is converted into the liquid. Amount of heat liberated $Q$ depends upon the mass of vapour ($m$) and the latent heat of vaporization ($L$). The same amount of heat has to be supplied to convert a liquid with mass $\left(m\right)$ to vapour.

Amount of heat released $Q$ = $mL$

But, the temperature remains the same during the phase transition.