Answer: Both assertion and reason are true and the reason explains the assertion.
- A The assertion is false but the reason is true
- B Both statements are true but the reason does not correctly explain the assertion
- C The assertion is true but the reason is false
- D Both assertion and reason are true and the reason explains the assertion
Correct answer: D. Both assertion and reason are true and the reason explains the assertion
Explanation: The small Li<sup>+</sup> has the highest charge density, giving the strongest hydration; hence its salts such as LiCl.2H<sub>2</sub>O are hydrated, unlike the larger alkali-metal ions.
Each s-block metal ion emits a characteristic flame colour because heating excites electrons to higher energy levels; light is emitted as they fall back, with the colour determined by the specific energy gap.
Concept context
Group 1 (alkali metals) and Group 2 (alkaline earth metals). Learn their reactions with water and air, important compounds like NaOH, Na₂CO₃, and CaCO₃, and anomalous behaviour of lithium and beryllium.