The pair of elements having approximately equal ionisation potential is

Options

A. Al,Ga
B. Al,Si
C. Al,Mg
D. Al,B

Answer

A

Explanation

In case of Ga there are `10`d - electrons in the penultimate energy shell which shield the nuclear charge less effectively, the outer electron is held firmly by nucleus. As a result, the ionisation energy remains nearly the same as that of aluminium inspite of the fact that atomic size increases.