Question

A compound is 52.17 % C, 13.04 % H and 34.78 % O. What is its empirical formula?

Answer 1

assume you have 100 grams of the stuff.
then you have
52.17gC, convert to moles of C
13.04gH, convert to moles of H
34.78gO, conver to moles of O

Now look at the mole ratio. It is easiest if yo take the smaller number, and divide it into the others. In my head, I see something like this
C 4, H12, O4
then dividing it in my head
CH3O or CH2OH

do it with your calculator.