A compound is 86% carbon and 14% hydrogen by mass. What is the empirical formula for this compound?

First, convert grams of the elements to moles. Then you divide by the smallest number of moles to get the lowest whole number ratio.

86g C*1 mol C/12g C = 7.2 mol C/7.2 = 1

14 g H*1 mol H/1g H = 14 mol H/7.2 = 2

So the empirical formula is C1H2