The correct order of electronegativity for given elements is:

Solution

Chemistry ma’am · 4 steps

Put the Pauling values side by side: Br leads, and At only just edges past P.

1. The two trends. Electronegativity rises across a period and falls down a group. When two elements are in different groups and periods, use the Pauling values to settle the order.

   Element	Position	Pauling value
   Br	Group 17, period 4	2.96
   C	Group 14, period 2	2.55
   At	Group 17, period 6	2.2
   P	Group 15, period 3	2.19

2. Why C beats P. P is one group to the right of C, but it is also one period lower. Its extra shell puts the valence electrons farther from the nucleus. The size effect wins, so C (2.55) is ahead of P (2.19).
3. Why At beats P. At is the heaviest halogen, so its value falls a long way, to about 2.2. That is still a little above P at 2.19.
4. So. The order is Br > C > At > P, which is option (b).

The idea to keep. Going down one period usually lowers electronegativity more than going one group right raises it. When two elements sit diagonally apart, compare their Pauling values.

Answer from the NTA final answer key. Solution by PrepWiser.