Question

$4g$ of hydrogen reacts with $20g$ of oxygen to form water. The mass of water formed is

• A. 24 g
• B. 36 g
• C. 22.5 g
• D. 40 g

Answer 1

Answer: (C)

$\underset{4g}{2H_2}+\underset{32g}{O_2}⟶\underset{36g}{2H_{2}O}$
When $4g$ of $H_2$ reacts with $32g$ of $O_2$ gives $36g$ of $H_{2}O$.
Now present oxygen is $20g$
$\therefore O_2$ will be the limiting reagent and $H_{2}O$ will be calculated from $O_2$,
$\therefore 32g$ of $O_2$ given $=36g$ of $H_{2}O$
$20g$ of $O_2$ given $=\frac{36}{32}\times 20=22.5g{H}_{2}O$