In hydrogen peroxide $\left(H_2{O}_2\right)$, the proportion of hydrogen by mass is :

The answer: The ratio of Hydrogen: Oxygen is 1:16

The molar mass of hydrogen peroxide is 34.01468 g/ mol.

Hydrogen has an atomic mass of 1.00794 g/mol

oxygen's atomic mass is 15.9994 g/mol.

There are two atoms of each element in hydrogen peroxide, so multiply these atomic masses by 2, and then add the products together.

1.00794 g/mol x 2 = 2.01588 g/mol or 2 g/mol

15.9994 g/mol x 2 = 31.9988 g/mol or 32 g/mol

So the ratio for Hydrogen and Oxygen is 2: 32, that is equal to 1: 16.