Question

Water molecules have hydrogen and oxygen in the ratio of 1: 8 by mass. Find the ratio of number of atoms of elements in water molecules.

Answer 1

Ratio of number of moles 1 /1 ∶ 8/ 16 

Number of moles = Mass / Atomic mass

Number of moles of hydrogen = 1/ 1 = 1 

Number of moles of oxygen = 8 /16 = 1/ 2 

Since ratio of number of moles 2:1 

Therefore ratio of number of molecules will also be 2:1.