Draw the atomic orbit structure diagram for formation of -

(a) hydrogen molecule

(b) chlorine molecule

(c) oxygen molecule

(d) nitrogen molecule

[at. no. H=1, Cl=17, O=8, N=7]

State why water has two lone pairs of electrons in it's covalent molecule while ammonia has one lone pair.

Give reasons for formation of single covalent bond between two chlorine atoms and a double covalent bond between two oxygen atoms - during formation of a covalent chlorine molecule and formation of a covalent oxygen molecule, respectively.

With the help of an atomic orbit structure diagram - explain the formation of :

(a) carbon tetrachloride

(b) methane

[at. no. : C=6, Cl=17, H=1]