Among the statements (a) - (d), the correct ones are:
(a)Lithium has the highest hydration enthalpy among the alkali metals.
(b) Lithium chloride is insoluble in pyridine.
(c) Lithium cannot form ethynide upon its reaction with ethyne
(d) Both lithium and magnesium react slowly with
(a)Lithium has the highest hydration enthalpy among the alkali metals.
(b) Lithium chloride is insoluble in pyridine.
(c) Lithium cannot form ethynide upon its reaction with ethyne
(d) Both lithium and magnesium react slowly with
- (A)(a), (b) and (d) only
- (B)(a) and (d) only
- (C)(b) and (c) only
- (D)(a), (c) and (d) only✓ Correct
Answer: (D)
Solution
Lithium, being the smallest alkali-metal cation, has the greatest charge density and hence the highest hydration enthalpy of the group, so statement (a) holds. Its small size gives high polarizing power, making lithium chloride appreciably covalent and therefore soluble in a solvent like pyridine, so statement (b) is false. Lithium is not electropositive enough to form an ethynide with ethyne, so statement (c) holds. And through its diagonal relationship with magnesium, lithium, like magnesium, reacts only slowly with water, so statement (d) holds. The correct statements are (a), (c) and (d).
JEE Main · 2020 · 09 Jan 2020 · Shift 2 · Single correct option