Select the correct statement(s)/order(s):

Options

A. d-orbital can accommodate 10 electrons
B. `underset(2s^(2) 2p^(6) 3s^(1) (Na) overset(IE_1)(to) underset(2s^(2)2p^(6))(Na^(+)) overset(IE_2)(to) underset(2s^(2)2p^(5))(Na^(2+)) overset(IE_3)(to) underset(2s^(2)2p^(4) ) (Na^(3+))` , order of successive I.E. is `IE_1 lt IE_2 gt IE_3`
C. Number of unpaired electrons in `Co^(2+)` cation is greater than Number of unpaired electrons in `Co^(3+)` cation
D. First ionisation energy of Pt is greater than that of Pd

Answer

A, B, C, D

Explanation

Any orbital can accommodate maximum 2 electrons
(B) For same Z, successive I.E. increases due to increase in `(Z/e)`
(C ) `Co (27) , [Ar]3d^(7) 4s^(2)`
`Co^(2+) : [Ar]3d^(7) 4s^@` unpaired `e^(-)` = 3
`Co^(3+) : [Ar] 3d^(5) 4s^@` , unpaired `e^(-)` = 4
(D) I.E. of Pt (6 period) > I.E. of Pd (5 period) due to poor shielding effect of 4f subshell in 6th period.