Match List I with List II
| List I | List II |
| A. Lanthanum | I. +3, +4 |
| B. Praseodymium | II. +3 |
| C. Neodymium | III. +2, +3, +4 |
| D. Samarium | IV. +2, +3 |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A-II, B-I, C-III, D-IV
All lanthanoids show the +3 state. A few also show +2 or +4, where that gives an empty, half-filled or filled f subshell or comes close to it.
(A) Lanthanum — This matches (II) +3. La (4f05d16s2) loses its three outer electrons; \( \ce{La^3+} \) has a noble gas configuration.
(B) Praseodymium — This matches (I) +3, +4. Pr also shows +4, but only in its oxide \( \ce{PrO2} \).
(C) Neodymium — This matches (III) +2, +3, +4. Nd shows +3, the +4 state in its oxide and also +2.
(D) Samarium — This matches (IV) +2, +3. Samarium behaves like europium and shows both +2 and +3.
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| – | – | – | 02-06 S3 31-05 S1 | – |