# Question follows after the explosion :Mole concept 3...

Chemistry Level 3

$$5\text{ mL}$$ of a gas containing only carbon and hydrogen was mixed with $$30\text{ mL}$$ of oxygen and the mixture was exploded by means of an electric spark.

After the explosion, the volume of the mixed gases remaining was $$25\text{ mL}.$$

On adding solution of concentrated $$\text{KOH},$$ the volume shrunk to $$15\text{ mL},$$ the residual gas being pure oxygen. All the gases have been reduced to NTP. The molecular formula of the gas with carbon and hydrogen only can be expressed as $\text{C}_n \text{H}_m.$ Find the sum $$\displaystyle{n+m}.$$

Note

• $$n$$ and $$m$$ are positive integers.
• This is a classical 1979 IIT JEE problem.
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