The molecular formula is ALWAYS, a whole number multiple of the empirical formula....and of course the multiple might be one...
And so we can write....
{empirical formula}n=molecular formula
And taking the given molecular mass of 70.13⋅g⋅mol−1
n=70.13⋅g⋅mol^−1/(12.011+1.00794×2)⋅g⋅mol−1=5
And so....
{CH2}×5=C5H10
