Amongst the following elements whose electronic configuration are given below, the one having the highest ionisation enthalpy is

1. [Ne]3s23p1

2. [Ne]3s23p3

3. [Ne]3s23p2

4. [Ar]3d104s24p3

Hint: Left to right across the period ionization energy increases and down the group ionization energy increases.

Step 1:

The electronic configuration represents
 
[Ne]3s23p1 represents aluminium 
[Ne]3s23p3 represents phosphorus
[Ne]3s23p2 represents silicon
[Ar]3d104s24p3 represents arsenic
 
Step 2:
 
Aluminium, silicon and phosphorus same period and left to right across the period ionization energy increases. Arsenic belongs to phosphorus group and position of arsenic just belong phosphorus. Down the group ionization energy decreases. Hence, [Ne]3s23p3 has the maximum ionization enthalpy.