Statement-I : The correct order of Ionization energy is $Na > Mg > Al > Ar$ Statement-II : Among the following elements $Sc, Ca$ and $Mg, Ca$ has highest $3^{rd}$ Ionisation Energy.
(2) Statement-I is correct but Statement-II is incorrect
(3) Statement-I is incorrect but Statement-II is correct
(4) Both Statement I and Statement II are incorrect
Show Solution
The Correct Option isD
Solution and Explanation
Trends in Ionization Enthalpy and electronic configurations.
LOGIC:
1. Statement-I: Ar is a noble gas and must have the highest IE. Na is an alkali metal and has the lowest in its period. The order $Na > ... > Ar$ is totally wrong. Statement-I is FALSE.
2. Statement-II: To find $3^{rd}$ IE, we look at the stability of the $M^{2+}$ ion. $Mg^{2+}$ and $Ca^{2+}$ both have octet configurations. Removing an electron from $Mg^{2+}$ (smaller) is harder than from $Ca^{2+}$ (larger). $Sc^{2+}$ has one $3d$ electron, so it's easiest to ionize. Hence, $Mg$ has the highest $3^{rd}$ IE, not $Ca$. Statement-II is FALSE.
3. Correct choice: (4).
