Question

The first element of group different form its congeners, i.e. other members of the group in many ways. These differences may be due to the following:
i. Small size of atom and ion.
ii. High electronegativity.
iii. Non-availibility of low lying d-orbitals.
The first element of a group shows resemblence with the second element of the adjacent group on the right. This is known as diagonal relationship.
Metal `(M)+N_(2)rarr` Nitride `overset(H_(2)O)underset("Hydrolysis")rarr NH_(3)`
Metal (M) can be
A. Li
B. Na
C. K
D. Mg

Answer 1

Correct Answer - A::D
`6Li+N2 rarr 2Li_(3)N`
`3H_(2)O+Li_(3)N rarr 3LiOH+NH_(3)`
`6Mg+N_(2)rarr 2Mg_(3)N`
`Mg_(3)N+3H_(2)O rarr 3Mg(OH)_(2)+NH_(3)`
Due to the small size of cation, `M(o+)` and anion `N6(3-)`, lattice energy of nitride formed is high and hence `Li^(o+)` and `Mg^(2+)` form stable nitride.