The bromine atom possesses `3s` electrons. It contains six electrons in `2p` orbitals, six electrons in `3p` orbitals and five electrons in `4p` orbitals. Which of these electrons experience the lower effective nuclear charge?

Explanation

for n=4 and l=2 , the obital occupied is 4d.
for n=3 and l=2 , the orbital occupied is 3d.
for n=4 and l =1 , the orbital occupied is 4p
hecnce ,the six electrons i.e 1,2,3,4,5 and 6 are present in the 4d, 3d, 4p, 3d, 4p , and 4p obitals respectively.
thereforem the inceasing the increasing order of energies is `5 ( 3p) lt 2(3d) = 4(3d) lt3(4p) = 6(4p) lt 1 (4d)`