$A$ liquid boils when its vapour pressure equals

Why does food cook faster in a pressure cooker?

The height of a mercury barometer is $75 \ cm$ at sea level and $50 \ cm$ at the top of a hill. The ratio of the density of mercury to that of air is $10^4$. The height of the hill is ....... $km$.

Describe the mercury barometer for the measurement of atmospheric pressure.

$A$ barometer kept in an elevator reads $76 \, cm$ when the elevator is accelerating upwards. The most likely pressure inside the elevator (in $cm$ of $Hg$) is ........

Why does an air bubble formed in water grow in size as it rises from the bottom to the surface? Explain.