Question

molecular mass of H2o

Answer 1

atomic mass of oxygen - 16
atomic mass of hydrogen - 1
molecular mass of water (H2O) = 2 × (atomic mass of hydrogen) + 1 × (atomic mass of oxygen)
= (2 × 1) + 16
= 2 + 16 = 18

Answer 2

atomic mass of hydrogen=1.008
since there are two hydrogen atom: 2*1.008=2.016
Atomic mass of oxygen=16.0002
So,the total molecular mass =2.016+16.0002
                             =18.0162