Hydrogenation of vegetable ghee at $25°\mathrm{C}$ reduces pressure of ${\mathrm{H}}_2$ from 2 atm to 1.2 atm in 30 minutes. The rate of reaction in terms of molarity per second is

Hydrogenation of vegetable ghee at 25 of zero order reaction

Rate(r)=K

For zero order reaction $\mathrm{K}=\frac{\mathrm{x}}{\mathrm{t}}$

Change in pressure = 0.8atm

$\therefore \mathrm{PV}=\mathrm{nRT}$

Change in conc $\uparrow \left[\frac{\mathrm{n}}{\mathrm{V}}\right]=\frac{\mathrm{p}}{\mathrm{RT}}=\frac{0.8}{0.821\times 523}$=0.08163moles/Lt

$\therefore \mathrm{Rate}=\frac{\mathrm{Change} \mathrm{in} \mathrm{comcentration}}{\mathrm{time}}$

$=\frac{0.01863}{30\times 60}=1.03\times {10}^{-5} {\mathrm{moleL}}^{-1}{\mathrm{s}}^{-1}$