Question

Elements X and Y belong to Group 15. The difference between the electronegativity values of 'X' and phosphorus is higher than that of the difference between phosphorus and 'Y'. 'X' & 'Y' are respectively

• A. As & Bi
• B. Bi & N
• C. As & Sb
• D. N & As

Hint:

Electronegativity changes significantly between Period 2 and 3 elements, but less so down the rest of the group.

Answer 1

The Correct Option is D

Group 15 elements: N, P, As, Sb, Bi. Electronegativity (EN) decreases down the group.
We require $|EN(X) - EN(P)|>|EN(P) - EN(Y)|$.
The largest change in EN in a group often occurs between the first two members (N and P).
Test X=N, Y=As (Option D).
$|EN(N) - EN(P)|$: Difference between 2nd and 3rd period element. (Large jump).
$|EN(P) - EN(As)|$: Difference between 3rd and 4th period element. (Smaller jump).
Since $EN(N)>EN(P)>EN(As)$, the condition $|EN(N) - EN(P)|>|EN(P) - EN(As)|$ holds true.