Question

Choose correct order of increasing ionization enthalpy.

• A. S < P < As
• B. P < S < As
• C. As < S < P
• D. As < P < S

Answer 1

The correct option is C As < S < P

We know that across a period I.E increases and down a period I.E decreases, in general.

Phosphorous and Arsenic belong to group 15 whereas S belongs to group16.

Also P and S belong to same period and P has exactly half-filled orbitals.

Therefore, IE varies in the order As $<$ S $<$ P.