JEE Main202127 Jul 2021Evening ShiftChemistryClassification of Elements and Periodicity in PropertiesActual
The CORRECT order of first ionisation enthalpy is:
Options
- AMg < S < Al < P
- BMg < Al < S < P
- CAl < Mg < S < P
- DMg < Al < P < S
Correct answer
C. Al < Mg < S < P
Step-by-step solution
The ionization energy of the elements increases from left to right in the periodic table. The first ionization of magnesium is greater than that of aluminium because magnesium has a stable complete electronic configuration 1 s 2 2 s 2 2 p 6 3 s 2 , so it requires more energy to remove the first electron from it, whereas aluminium has electronic configuration 1 s 2 2 s 2 2 p 6 3 s 2 3 p 1 which need lesser energy than that of magnesium. Similarly, phosphorus has more ionisation energy than sulphur due to the half fi