PROBLEM $($please solve all parts and show all steps$)$

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$30\mathrm{.}1$ Spherical pellets of $1\mathrm{.}0$diameter are spray$-$painted with a very thin coat of paint. The paint contains a volatile solvent. The vapor pressure of the solvent at $298$K is $1\mathrm{.}17$ x $10^4$Pa$,$and the diffusivity of the solvent vapor in air at $298$ K is $0\mathrm{.}0962$ cm$^2/$s$.$ The amount of solvent in the wet paint on the pellet is $0\mathrm{.}12$g solvent per cm$^2$ of pellet is $0\mathrm{.}12$ g solvent per cm$^2$ of pellet surface area. The molecular weight of the solvent is $78$ g$/$gmole$.$

a$.$Detemine the minimum time to dry the painted pellet if still air at $298$K and $1\mathrm{.}0$ atm surrounds the pellet.

$$b$.$ Determine the time to dry the painted pellet if air at $298$ K and $1\mathrm{.}0$atm pressure flows around the pellet at a bulk velocity of $1\mathrm{.}0$ m$/$s$.$