The configuration of Cr atom is `3d^(5)4s^(1)` but not `3d^(4)4s^(2)` due to reason `R_(1)` and the configuration of Cu atom is `3d^(10)4s^(1)` but not `3d^(9)4s^(2)` due to reason `R_(2).R_(1) and R_(2)` are:

Options

A. `R_(1):` The exchange energy of `3d^(5)4s^(1)`: is greater than that of `3d^(4)4s^(2)`
`R_(2):` The exchange energy of `3d^(10)4s^(1)` is greater than that of `3d^(9)4s^(2)`.
B. `R_(1)`: `3d^(5)4s^(1)` and `3d^(4)4s^(2)` have same exhange energy but `3d^(5)4s^(1)` is spheriaclly symmetrical.
`R_(2)`: `3d^(10)4s^(1)` is also shpherically symmetrical.
C. `R_(1)`: `3d^(5)4s^(1)` has grater exhange energy than `3d^(4)4s^(2)`.
`R_(2):3d^(10)4s^(1)` has spherical symmetry.
D. `R_(1):3d^(5)4s^(1)` has greater energy than `3d^(4)4s^(2)`.
`R_(2):3d^(10)4s^(1)` has greater energy than `3d^(9)4s^(2)`.

Answer

C

Explanation

`3d^(5)4s^(1)` is correct because it has greater exchange possibilities of unpaired electron.
`3d^(10)4s^(1)` is correct because `3d^(10)` orbitals are spherically symmetrical.