Contains 63.65% nitrogen and 36.35% oxygen by mass what is the empirical formula for this compound

The empirical formula is NO₂.

Assume that you have 100 g of the compound.

Then you have 63.65g N and 36.35 g O.

Now, we must convert these masses to moles and find their ratios.

From here on, I like to summarize the calculations in a table.

Element Mass/g Moles Ratio Integers

N 63.65 4.543 1 1

O 36.35 2.2719 2.000 2

The empirical formula is NO₂.