JEE Main 2024 · 8 April · morning · Single correct · +4 / −1
Match List I with List II
Choose the correct answer from the options given below:
| LIST I (Molecule) | LIST II (Shape) | ||
|---|---|---|---|
| A. | NH₃ | I. | Square pyramid |
| B. | BrF₅ | II. | Tetrahedral |
| C. | PCl₅ | III. | Trigonal pyramidal |
| D. | CH₄ | IV. | Trigonal bipyramidal |
- (a) A-II, B-IV, C-I, D-III
- (b) A-III, B-I, C-IV, D-II
- (c) A-IV, B-III, C-I, D-II
- (d) A-III, B-IV, C-I, D-II
Answer and solution
Answer (b) A-III, B-I, C-IV, D-II
Solution
Chemistry ma’am · 3 steps
Count bond pairs and lone pairs on the central atom; the lone pairs are what change the shape.
- Count electron pairs. Take the central atom's valence electrons and subtract one for each bond. Every two left over make one lone pair.
- Name the shape. All the pairs together set the arrangement. The shape is named only from where the atoms sit, so a lone pair takes up a corner that you do not count.
Molecule Bond pairs Lone pairs Shape NH₃ 3 5 - 3 = 2 electrons, so 1 trigonal pyramidal (III) BrF₅ 5 7 - 5 = 2 electrons, so 1 square pyramid (I) PCl₅ 5 5 - 5 = 0 trigonal bipyramidal (IV) CH₄ 4 4 - 4 = 0 tetrahedral (II) - So. The match is A-III, B-I, C-IV, D-II, which is option (b).
The idea to keep. Electron pairs set the arrangement, but the shape is named from the atoms alone. Five bonds with no lone pair is trigonal bipyramidal. Five bonds with one lone pair is a square pyramid.
Answer from the NTA final answer key. Solution by PrepWiser.