Match List I with List II
| List I | List II |
| A. \(Ni^{2+}\) | I. Pink |
| B. \(Cu^{2+}\) | II. Purple |
| C. \(Mn^{2+}\) | III. Green |
| D. \(Ti^{3+}\) | IV. Blue |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → A-III, B-IV, C-I, D-II
Transition metal ions with partly filled d orbitals are coloured. Light of a certain part of the visible spectrum excites an electron from a lower d orbital to a higher one (a d–d transition); the colour seen is the complementary colour of the light absorbed. The d-electron count of each ion is worked out first (4s electrons are removed before 3d):
A. \( \ce{Ni^{2+}} \) — This matches III. Green. Ni (Z = 28) is [Ar] 3d8 4s2; \( \ce{Ni^{2+}} \) is [Ar] 3d8.
B. \( \ce{Cu^{2+}} \) — This matches IV. Blue. Cu (Z = 29) is [Ar] 3d10 4s1; \( \ce{Cu^{2+}} \) is [Ar] 3d9.
C. \( \ce{Mn^{2+}} \) — This matches I. Pink. Mn (Z = 25) is [Ar] 3d5 4s2; \( \ce{Mn^{2+}} \) is [Ar] 3d5 (pale pink).
D. \( \ce{Ti^{3+}} \) — This matches II. Purple. Ti (Z = 22) is [Ar] 3d2 4s2; \( \ce{Ti^{3+}} \) is [Ar] 3d1.
Shortcut: A-III and B-IV appear in Options (1) and (2); C-I (\( \ce{Mn^{2+}} \) pink) leaves only Option (2).
NCERT (2026-27 edition):
Formation of Coloured Ions – …
