Question

Which of the following order(s) is/are correct ?

• A. $N{H}_3<P{H}_3<As{H}_3\left(Acidic\right)$
• B. $Li<Be<B<C\left(Basic\right)$
• C. $A{l}_2{O}_3<MgO<N{a}_{2}O<K_{2}O\left(Basic\right)$
• D. $L{i}^{+}<N{a}^{+}<K^{+}<C{s}^{+}\left(Ionicradius\right)$

Answer 1

Answer: (A), (C), (D)

The correct options are
A $N{H}_3<P{H}_3<As{H}_3\left(Acidic\right)$
C $A{l}_2{O}_3<MgO<N{a}_{2}O<K_{2}O\left(Basic\right)$
D $L{i}^{+}<N{a}^{+}<K^{+}<C{s}^{+}\left(Ionicradius\right)$

(A) On moving down the group, the basic character of hydrides decreases and the acidic character increases, with increase in the ionic size, as the lone pair of electron becomes more diffuse and less available for donation.
(B) On moving from left to right in a period, the basic nature decreases due to increase in the effective nuclear charge as the electrons become more tightly held.
(C) On moving from left to right in a period, the basic nature decreases due to increase in the effective nuclear charge as the electrons become more tightly held. Thus sodium oxide is a strong base whereas aluminium oxide is amphoteric.
On moving down the group from top to bottom, the basic character of oxides increases.
(D) On moving down the group of alkali metals, the ionic radius increases as new shells of electrons are added.