Question

Ionisation enthalpy (DᵢH₁kJ mol⁻¹) for the
elements of Group 13 follows the order.
(a) B > Al > Ga > In > Tl
(b) B < Al < Ga < In < Tl
(c) B < Al > Ga < In > Tl
(d) B > Al < Ga > In < Tl

Answer 1

Answer:

c) is the answer.....................

Answer 2

(a) B > Al > Ga > In > Tl

Explanation:

As we move from up to down a group of the periodic table, the ionisation energy of the element decreases.

Ionisation energy of the elements are:

B - 801; Al - 577, Ga - 579; In - 558; and Tl -589 kJ/mol.

The ionisation energy of both A1 and Ga is nearly the same. The increase in ionisation energy from In to Tl is due to poor screening effect of 14f electrons present in the inner shell.

Option A is the answer.