Question

The incorrect statement among the following is

• 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 the third ionisation potential of $Al$

Answer 1

Answer: (B)

The second ionisation potential of $Mg$ is greater than the second ionisation potential of $Na$

Answer 2

I.E.(II) of $Na$ is higher than that of $Mg$ because in case of $Na$, the second $e^{-}$ has to be remove from the noble gas core while in case of $Mg$ removal of second $e^{-}$ gives a noble gas core.

$Mg$ has high first ionisation potential than $Na$ because of its stable $ns^{2}$ configuration.