Mothballs are solid Naphthalene that vaporizes directly at room temperature. A handful of $1$ cm diameter mothballs are spaced apart on a thread and hung in the back of a closet that is deep. The closet is open to the room at an average temperature of $300$K and there is no detectable trace of Naphthalene odor in the room. Determine the time before the mothballs have completely evaporated. The diffusivity of Naphthalene in air can be taken as $6\mathrm{.}92*10^-7$ m$^2/$s and its vapor pressure at room temperature is $74$ Pa and atmospheric pressure is $101$ KPa.