JEE Main 2021 · 22 July · evening · Single correct · +4 / −1
Match List-I with List-II
Choose the correct answer from the options given below :
| List-I (Elements) | List-II (Properties) | ||
|---|---|---|---|
| (a) | Ba | (i) | Organic solvent soluble compounds |
| (b) | Ca | (ii) | Outer electronic configuration 6s² |
| (c) | Li | (iii) | Oxalate insoluble in water |
| (d) | Na | (iv) | Formation of very strong monoacidic base |
- (a) (a)-(ii), (b)-(iii), (c)-(i) and (d)-(iv)
- (b) (a)-(iv), (b)-(i), (c)-(ii) and (d)-(iii)
- (c) (a)-(iii), (b)-(ii), (c)-(iv) and (d)-(i)
- (d) (a)-(i), (b)-(iv), (c)-(ii) and (d)-(iii)
Answer and solution
Answer (a) (a)-(ii), (b)-(iii), (c)-(i) and (d)-(iv)
Solution
Chemistry ma’am · 3 steps
Start with the one fact you cannot argue with: only barium, in period 6, has a 6s² outer shell.
- Fix barium first. Barium is in group 2 and period 6, so its outer configuration is 6s². Calcium is 4s², lithium is 2s¹ and sodium is 3s¹, so (ii) can only go to Ba.
- Monoacidic base. A monoacidic base has one OH⁻ per formula unit, so it must come from a group 1 metal. NaOH is a very strong base. LiOH is weaker because the small Li⁺ holds OH⁻ more tightly, and Ca(OH)₂ has two OH⁻.
Element Property Reason Ba (ii) 6s² Group 2, period 6 Ca (iii) oxalate insoluble in water CaC₂O₄ is the white precipitate used to test for Ca²⁺ Li (i) soluble in organic solvents Tiny Li⁺ polarises anions, so LiCl is partly covalent and dissolves in ethanol Na (iv) very strong monoacidic base NaOH, one OH⁻, fully ionised - So. The match is Ba-(ii), Ca-(iii), Li-(i), Na-(iv), which is option (a).
The idea to keep. Lithium's odd behaviour, like covalent compounds that dissolve in organic solvents, comes from its very small, highly polarising ion. Remember it with Li's diagonal link to Mg.
Answer from the NTA final answer key. Solution by PrepWiser.