Which of the following neutral elements has the same electron configuration as the bromide ion, br−?
a) iodine
b) krypton
c) chlorine
d) argon

B) krypton

Explanation:

Electron configuration of Br: [Ar] 3d10 4s2 4p5

Since we have the bromide ion with a negative charge, Br's atom acquired an electron and therefore another electron is added to the electronic configuration .

Electron configuration of Br-: [Ar] 3d10 4s2 4p6

And now this electronic configuration coincides with that of Krypton as we see below :

Electron configuration of Kr: [Ar] 3d10 4s2 4p6

when jerome paddle in flowing river towards east the net speed of jerome will increase

so the net speed of jerome will be given as

now the speed of paul will be same as it is given as he is running on the ground

so

so here we can say since the speed of jerome is more so he will win the race

now as we know the distance so the time difference is given as

so jerome will reach first and the time difference will be 203.55 s or 3.4 min