20 mL of CO was mixed with 50 mL of oxygen and the mixture was exploded. On cooling, the resulting mixture was shaken with KOH. Find the volume of the gas that is left.

Explanation

To solve the problem step by step, we will follow the chemical reaction and stoichiometry involved in the reaction of carbon monoxide (CO) with oxygen (O2).

### Step 1: Write the balanced chemical equation
The reaction between carbon monoxide and oxygen can be represented as:
\[ 2 \text{CO} + \text{O}_2 \rightarrow 2 \text{CO}_2 \]

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