Question

The incorrect statement among the following:

• A. The first ionisation potential of $Al$ is less than the first ionisation potential of $Mg$.
• B. The second ionisation potential of $Mg$ is greater than the second ionisation potential of $Na$.
• C. The first ionisation potential of $Na$ is less than the first ionisation potential of $Mg$.
• D. The third ionisation potential of $Mg$ is greater than third ionisation potential of $Na$.

Answer 1

The correct option is B The second ionisation potential of $Mg$ is greater than the second ionisation potential of $Na$.

Option (a): Given statement is correct. In a period, the element of the $2nd$ group has higher first ionisation potential than the element of group $13$.
Option (b): Given statement is incorrect. $M{g}^{+}$ ion requires less energy for further ionisation than $N{a}^{+}$ ion because of the noble gas configuration of $Na+$ ion.
Option (c): Given statement is correct. Ionisation energy increases from left to right in a period.
Option (d): Given statement is correct. $M{g}^{2+}$ ion has a noble gas configuration hence it will be having greater ionisation energy than $N{a}^{2+}$ ion.