Question

In s-block chemistry, quicklime and slaked lime are represented as MO and \( \mathrm{M(OH)_2} \) respectively. Identify the metal M.

• A. Sodium
• B. Calcium
• C. Potassium
• D. Magnesium

Hint:

To remember the difference: Quicklime is "dry" (\(\text{CaO}\)), and Slaked lime is "wet" (it has been "slaked" or satisfied with water to become \(\text{Ca(OH)}_2\)).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
Quicklime and slaked lime are common names for specific compounds of alkaline earth metals (Group 2 of the s-block). The formulas MO and M(OH)\(_2\) indicate that the metal M has a valency of +2.

Step 2: Detailed Explanation
1. Quicklime: This is the common name for Calcium Oxide (\(\text{CaO}\)). It is produced by the thermal decomposition of limestone (\(\text{CaCO}_3\)). 2. Slaked Lime: When quicklime is treated with water, it undergoes a highly exothermic reaction to form Calcium Hydroxide (\(\text{Ca(OH)}_2\)), which is known as slaked lime. \[ \text{CaO} + \text{H}_2\text{O} \to \text{Ca(OH)}_2 \] 3. Other Options: - Sodium and Potassium are Group 1 metals (valency +1). - Magnesium Oxide is called Magnesia, not quicklime.

Step 3: Final Answer
The metal M is Calcium.