Answer: Sodium.
- A Sodium
- B Calcium
- C Magnesium
- D Beryllium
Correct answer: A. Sodium
Explanation: Sodium is highly reactive with air and water and is stored submerged in kerosene oil.
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.