$A$ mixture of equal masses of two gases with molecular weights $4$ and $40$ has a total pressure of $1.1 \, atm$. The partial pressure of the lighter gas in the mixture is ............ $atm$.

Name two phenomena that can be explained on the basis of surface tension.

Pressure of a gas in a vessel can be measured by

The temperature at which the vapour pressure of a liquid becomes equal to the atmospheric pressure is known as:

The rate of diffusion of hydrogen is......

Fill in the blanks:
$(1)$ The properties of gases were first measured by ......... .
$(2)$ The dipole-dipole interaction energy between stationary polar molecules is proportional to .......... .
$(3)$ The interaction energy between rotating polar molecules is proportional to .......... .
$(4)$ The bond energy of a hydrogen bond is about ......... $kJ \ mol^{-1}$.