• Brainly User
This question is from mole concept and in mole we study a law named Ideal gas law by avagadro.A/c to which all the gases occupies same volume under similar conditions of tempurature and pressure so the no of moles is going be equal
we can take them as in ratio
10 : 40: 50
and as there in no carbon in h2o that means all the carbon has added to co2 from hydrocarbon
so we can write that 
10ml of hydrocarbon produces 40ml of co2
or in ratio as 10:40 or 1:4
and the hydrogens have benn added to h20
so 10ml of hydrocarbon produces 50ml of h2o
or in ratio as 10:50or 1:5
and if there are 5 [h2o] that means 10hydrogens
so 1 mole of hydrocarbon has 10 moles of hydrogen 
so that there are 4 carbons and 10 hydrogen