Answer: Mg(OH) 2.
- A Mg(OH)<sub>2</sub>
- B MgO
- C MgCO<sub>3</sub>
- D MgSO<sub>4</sub>
Correct answer: A. Mg(OH)<sub>2</sub>
Explanation: Milk of magnesia is a suspension of magnesium hydroxide Mg(OH)<sub>2</sub> in water, used as an antacid and laxative.
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.