Question

What does this mean hydrogen and oxygen combine ina fixed ratio of 1:8

Answer 1

Hydrogen and oxygen combine as H2O to form water.

That is 2 atoms of hydrogen combine with one atom of oxygen.

atomic mass of hydrogen is 1u and of oxygen is 16u.

so total mass of hydrogen combining is (1*2)=2u and oxygen is (16*1)=16u

if you simplify them 2u:16u,you get 1:8.

Therefore hydrogen and oxygen combine in 1:8 ratio by mass.