Which of the following statement is correct ?

Options

A. Ionisation energiest of elements decrease along the period.
B. Ionisation energies of the IIA group elements are less than that of the corresponding III A group elements.
C. Ionisation energies of group 15 elements are less than that of the corresponding group 16 elements.
D. Ionisation energy of Ga is greater than Al.

Answer

4

Explanation

1. Generally ionisation energies increase along the period because size of atom decreases and nuclear charge increases.
2. Ionisation energies of IIA group elements are higher than those of corresponding IIIA group elements because removal of electron from `ns^(2)` configuration in IIA group elements is quite difficul, `e.g., Be lt B`.
3. Ionisation energies of group 16 elements are elss than those of corresponding in case of group 15 elements `,e.g., O lt N`.
`4.` Effective nuclear charge of Ga is greater because of poor shielding of `10d-`electrons ( Ga and Al has nearly same size ).