In water, the proportion of oxygen and hydrogen by mass is :

Wt of 1mole of hydrogen=1g

Wt of 1mole of oxygen= 16g

So water is 2H +O

So the ratio of the mass of H to O is

=Mass of 2H/mass of O

= (2 x 1)/16 = 2/16

=1/8

So the ratio of Hydrogen and Oxygen is 1:8 in the respective above order.