Question

A mixture of $100$ mL of $CO,C{O}_2$ and $O_2$ was sparked. When the resulting gaseous mixture was passed through $KOH$ solution, contraction in volume was found to be $80$ mL, the composition of initial mixture may be (in the same order):

• A. $30$ mL, $60$ mL, $10$ mL
• B. $30$ mL, $50$ mL, $20$ mL
• C. $50$ mL, $30$ mL, $20$ mL
• D. $20$ mL, $70$ mL, $10$ mL

Answer 1

Answer: (A), (B)

The correct options are
A $30$ mL, $60$ mL, $10$ mL
B $30$ mL, $50$ mL, $20$ mL

$KOH$ absorbs $C{O}_2$ gas, so contraction in volume is due to $C{O}_2$ absorption.
$2CO+O_2\to 2C{O}_2$, so total volume of $C{O}_2$ formed is $80$ mL.
(A) $10$ mL of $O_2$ reacts with $20$ mL $CO$ and $20$ mL $C{O}_2$ forms, so total volume of $C{O}_2$ is $80$ mL.
(B) $15$ mL of $O_2$ reacts with $30$ mL $CO$ and $30$ mL $C{O}_2$ forms, so total volume of $C{O}_2$ is $80$ mL.