Which of the following will be coloured in aqueous solution?
A. Mn2+
B. Sc3+
C. Zn2+
D. Co2+
E. Fe3+
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
A. Mn2+: [Ar]3d5
| ↑ | ↑ | ↑ | ↑ | ↑ |
B. Sc3+: [Ar]
No electrons in d-orbital.
C. Zn2+: [Ar]3d10
| ↑↓ | ↑↓ | ↑↓ | ↑↓ | ↑↓ |
D. Co2+: [Ar]3d7
| ↑↓ | ↑↓ | ↑ | ↑ | ↑ |
E. Fe3+: [Ar]3d5
| ↑ | ↑ | ↑ | ↑ | ↑ |
A, D and E are coloured as they contain partially filled d-orbital and d-d transition can take place which is not the case with B and C.