What is the relationship between viscosity and density?

$A$ gas sample of $1.47 \ L$ was collected over water at $30 \ ^\circ C$ and $744 \ mm \ Hg$ pressure. If the weight of the gas is $1.98 \ g$,what is the molar mass of the gas? (Assume the vapor pressure of water at $30 \ ^\circ C$ is $31.8 \ mm \ Hg$)

The vapor pressure of water at $80\,^oC$ is $355.5\, mm\, of\, Hg$. $A$ $100\, mL$ vessel contains $O_2$ saturated with water vapor at $80\,^oC$,and the total pressure is $760\, mm\, of\, Hg$. If the contents are transferred to a $50\, mL$ vessel at the same temperature,what will be the partial pressure of $O_2$ in $mm\, Hg$?

At $STP$,what is the actual volume occupied by the molecules of $1 \, \text{mol}$ of water vapor (i.e.,$\text{Avogadro's number} \times \text{volume of one molecule}$)?

The force $(F)$ required to maintain the flow of layers of a liquid is equal to ($A = \text{area of contact of layers}$,$dz = \text{distance between the layers}$,$du = \text{change in velocity}$,$\eta = \text{coefficient of viscosity}$)

Assertion : Wet air is heavier than dry air.
Reason : The density of dry air is more than density of water.