Which set of ions exhibit specific colours? (Atomic number of Sc = 21, Ti = 22, V=23, Mn = 25, Fe = 26, Ni = 28 Cu = 29 and Zn =30)

Options

A. `Sc^(3+) , Ti^(4+) , Mn^(3+)`
B. `Sc^(3+) , Zn^(2+) , Ni^(2+)`
C. `V^(3+) , V^(2+), Fe^(3+)`
D. `Ti^(3+) , Ti^(4+), Ni^(2+)`

Answer

C

Explanation

Explanation `V^(3+) , V^(2+) , Fe^(3+)` ions exhibit specific colours.
Atomic number of V = 23,
Electronic configuration of `V- [Ar]3d^3 4s^2`
Electronic configuration of `V^(2+) - [Ar]3d^3`
Electronic configuration of `V^(3+) -[Ar]3d^2`
Atomic number of Fe = 26
Electronic configuration of `Fe^(3+) [Ar]3d^(5)`
Since these ions have partially filled d-subshells, they exhibit colour. Most transition-metal ions have a partially filled d subshell.
As for other ions
Atomic number of Sc = 21
Electronic configuration of `Sc=[Ar]3d^(1)+ 4s^2`
Electronic configuration of `Sc^(3+)-[Ar] 3d^0`
Since d subshell is empty, it shows no colour
Atomic number of Ti = 22
Electronic configuration of `Ti- [Ar]3d^2 4s^2`
Electronic configuration of `Ti^(4+) - [Ar]3d^(0)`
Sinced subshell is empty it shows no colours
Atomic number of Mn = 25
Electronic configuration of `Mn-[Ar]3d^5 4s^2`
Electronic configuration of `Mn^(2+) [Ar]3d^5`
Since d subshell is partially filled, it shows colour.
Atomic number of Ni = 28
Electronic configuration of Ni- `[Ar]3d^(8) d^8 4s^2`
Electronic configuration of `Ni^(2+) [Ar]3d^8`
Since d subshell is partially filled, it shows colour
Atomic number of Zn = 30
Electronic configuration of `Zn - [Ar[ 3d^(10) 4s^2`
Electronic configuration of `Zn^(2+) -[Ar] 3d^(10)`
Since d subshell is full , it shows no colour.