Question

If $30$ $mL$ of $H_{2}$ and $20$ $mL$ of $O_{2}$ react to form water, what is left at the end of the reaction?

• A. $10$ $mL$ $of$ $H_{2}$
• B. $5$ $mL$ $of$ $H_{2}$
• C. $10$ $mL$ $of$ $O_{2}$
• D. $5$ $mL$ $of$ $O_{2}$

Answer 1

Answer: (D)

$2H_{2}+O_{2} \rightarrow 2H_{2}O$
Combining volume ratio of $H_{2}$ and $O_{2}$ $=2:1$
Here $H_{2}$ is limiting reactant. $30 \, ml$ of $H_{2}$ will react with $15 \, ml$ of $O_{2}$ and $5 \, ml$ of $O_{2}$ will remain unreacted at the end.