Question

40 mL of $CO$ was mixed with 100 ml of $O_2$ and the mixture was exploded. On cooling, the reaction mixture was shaken with $KOH$. The volume of gas left is:

• A. 60 ml of $O_2$
• B. 80 ml of $O_2$
• C. 20 ml of $CO$
• D. 40 ml of $C{O}_2$

Answer 1

The correct option is B 80 ml of $O_2$

$CO+\frac{1}{2}{O}_2\to C{O}_2$
40 ml 20 ml 40 ml
$\begin{array}{c}\downarrow KOH\\ absorbed\end{array}$

From the reaction, one mole of $CO$ reacts with a half mole of $O_2$ to form one mole of $C{O}_2$.

As 40mL of CO is present in the mixture, it will react with 20mL of $O_2$ to form 40mL of $C{O}_2$, which is later absorbed by $KOH$, so only gas left is remaining $O_2$.

Volume of $O_2$ left $=(100-20)=80ml$

Option B is correct.