Question

Find out the period number of the inert gas atom in which the total number of d-electron is equal to the difference in the number of total p-and s-electrons

Answer 1

Correct Answer - 4
First gas which contains d-electron is Kr.
`1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(10)4s^(2)4p^(6)`
Total number of d-electron = 10
Total number of p-electrons = 6+6+6=18
Total number of s-electrons = 2+2+2+2=8
Difference in total number of p-and s-electrons =18-8=10
So inert gas is `._(36)Kr`. Now since At. No. is 36 so, period no. is (4)