The atomic numbers of elements `X,Y`,and `Z` are `19,21`, and `23`, respectively. The number of eletron present in the `M` shells of these elements follows the order

Options

A. `Z gt X gt Y`
B. `X gt Y gt Z`
C. `Z gt Y gt X`
D. `Y gt Z gt X`

Answer

C

Explanation

`X (Z = 19): (1s^(2))/(K) (2s^(2)2p^(6))/(L)(3s^(2)3p^(6))/(M)(4s^(1))/(N)`
`Y(Z = 21): (1s^(2))/(K)(2s^(2)2p^(6))/(L)(3s^(2)3p^(6)3d^(1))/(M)(4s^(2))/(N)`
`Z(Z = 25):(1s^(2))/(K)(2s^(2)2p^(6))/(L)(3s^(2)3p^(6)3d^(5))/(M)(4s^(2))/(N)`
Thus, the correct of number of electrons in the `M` shell is
`Z(13) gtY(9) gt X (8)`