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.