Match List I with List II
| List I | List II |
| A. Oxidation state of \(Mn\) in \(MnO_2\) is | I. +2 |
| B. Most stable oxidation state of \(Mn\) is | II. +3 |
| C. Most stable oxidation state of \(Mn\) in \(MnO_4^-\) | III. +4 |
| D. Characteristic oxidation state of lanthanoids is | IV. +7 |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A-III, B-I, C-IV, D-II
Manganese (Z = 25, [Ar]3d54s2) shows oxidation states from +2 to +7. The most stable one is the state with a half-filled d subshell; the lanthanoids show one characteristic state common to the whole series.
(A) Oxidation state of Mn in \( \ce{MnO2} \) is — This matches (III) +4: x + 2(−2) = 0 gives x = +4.
(B) Most stable oxidation state of Mn is — This matches (I) +2. Losing the two 4s electrons gives \( \ce{Mn^{2+}} \): 3d5, a half-filled, extra-stable configuration.
(C) Most stable oxidation state of Mn in \( \ce{MnO4^{-}} \) is — This matches (IV) +7: x + 4(−2) = −1 gives x = +7, when all seven 3d and 4s electrons are used.
(D) Characteristic oxidation state of lanthanoids is — This matches (II) +3. All lanthanoids show +3; +2 and +4 occur only where they give an empty, half-filled or filled f subshell.
Shortcut: (A)-(III) appears only in Option (3).