Water is evaporating from a pool exposed to a breeze of ambient air at $300$ K$,1\mathrm{.}0132$ bar, and $25\%$ relative humidity. Assuming that mass transfer is due to molecular diffusion through a stagnant film of air of $80$ mm$,$ determine the following

$$ A$)$ the diffusivity of water in air using Hirschfeldre's equation

$$ B$)$ The model to evaluate the rate of evaporation of water

$$ C$)$ the initial rate of evaporation of water as a molar flux in Kmol$/$Cm$^2-$S

$$ D$)$ The time in hours for the water level to drop $1$ cm

$$ Given:

$$ M$($air$)=29$ g$/$mol;

$$ Water vapor pressure $($@$300$K$)=35\mathrm{.}31$ kPa

$$ Collision diameter $($air$)=3\mathrm{.}620$ Anstrong

$$ Collision diameter $($water$)=2\mathrm{.}640$ Anstrong

$$ E$/$K $($air$)=97$ K

$$ E$/$K $($water$)=809\mathrm{.}1$ K

$$ Dens. $($water$)=1$ g$/$cm$^3$

$1$ atm $=1\mathrm{.}0132$ bar $=101\mathrm{.}3$ kPa

$$ R $=8\mathrm{.}134$ kPa m$^3/$kmol$-$K

Hint $-$Relative humidity is the ratio of the partial Pressure of water to the equilibrium vapor pressure at the same temperature the answer