The first ionisation enthalpy of the elements C,N,P,Si are in the order of

Options

A. F `lt` S `lt` P `lt` B
B. P `lt` S `lt` B `lt` F
C. B `lt` P `lt` S `lt` F
D. B `lt` S `lt` P `lt` F.

Answer

D

Explanation

The outer electronic configurations of the given elements are
`B : 2s^(2) 2p^(1), P: 3s^(2) 3p^(3), S : 3s^(2) 3p^(4), F : 2s^(2) 2p^(5)`
Therefore, the choice should be
`BltSltPltF`
Fluorine being most electronegative has highest ionisation enthalpy.