$1.$ A zinc specimen exposed to an acid solution loses $75$ mg during a $36$ hr$.$ exposure. $($a$)$ Calculate the equivalent current flowing due to corrosion, $($b$)$ corrosion rate in microns$/$yr and $($c$)$ equivalent current density if the surface area is $200$ cm$2.$ Density of zinc: $7\mathrm{.}2$ g$/$cc and atomic weight: $65.$