Question

The increasing order of the first ionisation enthalpies of the elements B, P, S and F (lowest first) is

(a) F < S < P < B 

(b) P < S < B < F

(c) B < P < S < F 

(d) B < S < P < F.

Answer 1

Correct Option(d) B < S < P < F

Explanation:

Examine the posiirons in periodic table.

Ionisation enthalpy increases along a period due to increased nuclear charge and decreased atomic radii. While in a group, it decreases from top to bottom. Along with this trend ionisation enthalpy is highest for the elements possessing half filled and sable electronic confrgur.ation. 

Since, phosphorus is having stable half-filled configuration, Hence, orders B < S < P < F.