What Is the Molecular Formula of the Hydrocarbon in This Combustion Analysis?

[Ose90]

Homework Statement

6.0 cm^3 of a gaseous hydrocarbon was sparked with 34.5 cm^3 of oxygen. The volume of the gaseous products after cooling to room temperature was 22.5 cm^3. The volume was reduced to 4.5 cm^3 on passing the gases through aqueous potassium hydroxide. What is the molecular formula of hydrocarbon?

Homework Equations

The Attempt at a Solution

CxHy + ( x + y/4 ) O2 ----> x CO2 + Y/2 H2O

Is this equation correct?Do I miss out any product?

my doubts : First, I try calculating the volume of CO2 produced and It is 18cm^3 and the volume of H2O is apparently 4.5 cm^3. What should I do next?
How to find the volume of oxygen gas that has reacted? Should I convert them into moles by dividing the volume of room temperature? I'm confused :(

 

[chemisttree]

First, I try calculating the volume of CO2 produced and It is 18 cm³ and the volume of H₂O is apparently 4.5 cm³. What should I do next?
How to find the volume of oxygen gas that has reacted? Should I convert them into moles by dividing the volume of room temperature? I'm confused :(

You have found the volume of CO₂. Convert it to moles to determine 'x'. What remains is water vapor. Find the number of moles of that and determine 'y'.