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Q.
$4\, g$ of hydrogen reacts with $20\, g$ of oxygen to form water. The mass of water formed is
Some Basic Concepts of Chemistry
Solution:
$\underset{4\,g}{2 H _{2}}+ \underset{32\,g}{O _{2}} \longrightarrow \underset{36\,g}{2 H _{2} O}$
When $4\, g$ of $H _{2}$ reacts with $32\, g$ of $O _{2}$ gives $36\, g$ of $H _{2} O$.
Now present oxygen is $20 \,g$
$\therefore O _{2}$ will be the limiting reagent and $H _{2} O$ will be calculated from $O _{2}$,
$\therefore 32\, g$ of $O _{2}$ given $=36\, g$ of $H _{2} O$
$20\, g$ of $O _{2}$ given $=\frac{36}{32} \times 20=22.5\, g\, H _{2} O$