Match List-I (substance) with List-II (use).
| List-I (Substance) | List-II (Use) |
|---|---|
| (A) Cerium(IV) | (I) Mg-based alloys for bullets, shells and lighter flint |
| (B) Some individual lanthanoid oxides | (II) Polymerisation of alkynes and of other organic compounds such as benzene |
| (C) Mischmetall | (III) Phosphors in television screens |
| (D) Nickel complexes | (IV) Analytical reagent |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A-IV, B-III, C-I, D-II
Several d- and f-block elements and their compounds have special uses that follow from their properties.
(A) Cerium(IV) — This matches (IV) Analytical reagent. Ce(IV) is a strong oxidant (E° Ce4+/Ce3+ = +1.74 V), strong enough to oxidise water, but this reaction is very slow. So Ce(IV) is a good analytical reagent.
(B) Some individual lanthanoid oxides — This matches (III) Phosphors in television screens. Such oxides are used as phosphors in television screens and similar fluorescing surfaces.
(C) Mischmetall — This matches (I) Mg-based alloys for bullets, shells and lighter flint. Mischmetall is an alloy of a lanthanoid metal (about 95%) and iron (about 5%), and a good deal of it goes into these Mg-based alloys.
(D) Nickel complexes — This matches (II) Polymerisation of alkynes and of other organic compounds such as benzene. Nickel and its compounds are well known catalysts; these complexes are useful in such polymerisations.
NCERT (2026-27 edition):
4.5.3 Oxidation States – “…The Eo value for Ce4+/ Ce3+ is + 1.74 V which suggests that it can oxidise water. However, the reaction rate is very slow and hence Ce(IV) is a good analytical reagent.”
4.5.4 General Characteristics – “…A well known alloy is mischmetall which consists of a lanthanoid metal (~ 95%) and iron (~ 5%) and traces of S, C, Ca and Al. A good deal of mischmetall is used in Mg-based alloy to produce bullets, shell and lighter flint. Mixed oxides of lanthanoids are employed as catalysts in petroleum cracking. Some individual Ln oxides are used as phosphors in television screens and similar fluorescing surfaces.”
4.7 Some Applications of d- and f-Block Elements – “…Nickel complexes are useful in the polymerisation of alkynes and other organic compounds such as benzene.”