The ratio of rates of diffusion of helium $(He)$ to hydrogen $(H_2)$.

When the temperature is raised,the viscosity of a liquid decreases. This is because:

On a certain day,the humidity in the atmosphere is $1\%$. If the barometer reads $760 \ mm \ of \ Hg$,what will be the pressure of the dry gas in $mm \ of \ Hg$?

Define surface tension and provide its dimensions and $SI$ unit.

The total pressure exerted by a mixture of non-reacting gases is equal to the sum of the partial pressures of the individual gases under the same conditions. This is known as:

Fill in the blanks:
$(1)$ The forces of attraction and repulsion between molecules and atoms are called ....... .
$(2)$ The attractive intermolecular forces between molecules of a substance are also known as .............. .
$(3)$ London forces are also known by the name of ........... .
$(4)$ The mathematical form of Charles's Law is ........ .