Electronic configurations of four elements $A, B, C$ and $D$ are given below :\ (A) $1 s^{2} 2 s^{2

Question

Electronic configurations of four elements $A, B, C$ and $D$ are given below :\ (A) $1 s^{2} 2 s^{2} 2 p^{6}$\ (B) $1 s^{2} 2 s^{2} 2 p^{4}$\ (C) $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{1}$\ (D) $1 s^{2} 2 s^{2} 2 p^{5}$ 
Which of the following is the correct order of increasing tendency to gain electron?\

Professor PC Thomas Classes · Answer

(a) : $A$ is $\mathrm{Ne}(10): 1 s^{2} 2 s^{2} 2 p^{6}, B$ is $\mathrm{O}(8): 1 s^{2} 2 s^{2} 2 p^{4} C$ is $\mathrm{Na}(11): 1 s^{2} 2 s^{2} 2 p^{6} 3 s^{1}, D$ is $\mathrm{F}(9): 1 s^{2} 2 s^{2} 2 p^{5}$