Question

what is the atomicity of H2O and CH4

Answer 1

(i) H2O:
The molecular mass of water, H2O
= (2 × Atomic mass of hydrogen) + (1 × Atomic mass of oxygen)
= [2(1.0084) + 1(16.00 u)]
= 2.016 u + 16.00 u
= 18.016
= 18.02 u
(ii) CH4:
The molecular mass of methane, CH4
= (1 × Atomic mass of carbon) + (4 × Atomic mass of hydrogen)
= [1(12.011 u) + 4 (1.008 u)]
= 12.011 u + 4.032 u
= 16.043 u

Answer 2

Atomicity is the is number of atoms in a molecules...

so in H2O :---

2 hydrogen atom + 1 oxygen atom = 3 atoms

=) atomicity of H2O = 3

IN case of CH4 :---

1 Carbon atom + 4 hydrogen atom = 5 atoms

=) atomicity of CH4 = 5