Question

What happens when an astronaut heats ice at $-5^{o}C$ on the moon?

• A. It melts into water $-5^{o}C$.
• B. Its temperature rises and then melt at $0^{o}C$.
• C. It sublimates into vapours.
• D. It melts at temperature greater than $0^{o}C$.

Answer 1

Answer: (C)

It sublimates into vapours.

Any liquid will start to boil if the vapour pressure of the liquid is greater than the external pressure.When ice at $-5^{0}C$ is heated,the formed liquid water instantaneously vapourises as water posses a vapour pressure greater than zero.Hence ice sublimes directly into vapour.