Outermost electronic configurations of four elements A , B , C , D are given below: (A) 3 s 2 (B) 3 s 2 3 p 1 (C) 3 s 2 3 p 3 (D) 3 s 2 3 p 4 The correct order of first ionization enthalpy for them is

Step-by-step solution

(A) 3   s 2 → Mg (B) 3   s 2 3 p 1 → Al (C) 3   s 2 3 p 3 → P (D) 3   s 2 3 p 4 → S Al has one unpaired electron in its highest energy orbital 3 p , and Mg ' s highest energy orbital 3 s has the paired electrons. It is energetically favourable for all the electrons in an orbital to be paired, which means that breaking up this pair would require more energy. Compared to 16 th group, 15 group have high ionisation energy. It is because of the stable half filled configura