$A$ gaseous mixture was prepared by taking equal moles of $CO$ and $N_2$. If the total pressure of the mixture was found to be $1 \ atm$,the partial pressure of the nitrogen $(N_2)$ in the mixture is ............ $atm$.

Two gases $A$ and $B$ having the same volume,effuse through an orifice in $30$ and $10$ minutes respectively. The molar mass of $A$ is $162$. The molar mass of $B$ will be

Helium is added to the oxygen supply used by deep sea divers because

Which shape does a liquid have in its lowest energy state?

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 ......... $kJ \ mol^{-1}$.

What is the $SI$ unit of viscosity?