Question

The mass of iron (in g) which will be converted to its oxide by the action of $18$ g steam is :

Answer 1

$3Fe+4H_{2}0\to {Fe}_3{O}_4+4H_2$
$4\times 18$ g $H_{2}0$ reacts with $3\times 56$ g $Fe$.
$\therefore 18$ g $H_{2}O$ reacts with $\frac{3\times 56\times 18}{4\times 18}$ g $=$ $42$ g of $Fe$.