Chemistry - Mole Concept Question with Solution | TestHub

$\because$ Only one mole of total gases are evolved and ${\mathrm{H}}_2\mathrm{O}$ decomposes as

${\mathrm{H}}_2\mathrm{O}\stackrel{\mathrm{decomposition}}{\to }{\mathrm{H}}_2+\frac{1}{2}{\mathrm{O}}_2$

i.e. total moles $=1+\frac{1}{2}=\frac{3}{2}$ moles by one mole of ${\mathrm{H}}_2\mathrm{O}$

Now,

$\because \frac{3}{2}$ moles of gases are evolved by $=1 \mathrm{mole}$ of ${\mathrm{H}}_2\mathrm{O}$

$\therefore 1 \mathrm{mole}$ of gases are evolved by $=\frac{1}{3/2}=\frac{2}{3}$

Hence, $1 \mathrm{mole}$ of total gases are evolved by $\frac{2}{3} \mathrm{mole}$ of ${\mathrm{H}}_2\mathrm{O}$.