Which of the following statements regarding the oxides of alkali and alkaline earth metals is correct?

Options

A. The reactivity of `K_(2)O` towards water is more than that of `Na_(2)O`
B. The oxides of alkaline earth metals are more basic than those of alkali metals
C. MgO is used as a refractory material for lining of electric furnaces
D. The milk of lime and lime water are two different solutions

Answer

To determine which of the statements regarding the oxides of alkali and alkaline earth metals is correct, we will analyze each statement step by step.

### Step 1: Analyze Statement A
**Statement A:** The reactivity of K2O toward water is more than that of Na2O.

**Analysis:**
- K2O (potassium oxide) is indeed more reactive with water than Na2O (sodium oxide). This is because potassium is lower in the group than sodium, which means K2O is more basic due to the larger ionic size of K+, leading to a stronger tendency to react with water to form KOH.

**Conclusion:** Statement A is **true**.

### Step 2: Analyze Statement B
**Statement B:** The oxides of alkaline earth metals are more basic than those of alkali metals.

**Analysis:**
- This statement is incorrect. The oxides of alkali metals (like Na2O, K2O) are generally more basic than those of alkaline earth metals (like MgO, CaO). As we move from left to right in the periodic table, the basicity decreases due to the decrease in metallic character. Therefore, alkali metal oxides are more basic than alkaline earth metal oxides.

**Conclusion:** Statement B is **false**.

### Step 3: Analyze Statement C
**Statement C:** MgO is used as a refractory material for lining electric furnaces.

**Analysis:**
- MgO (magnesium oxide) has a very high melting point (around 2852 degrees Celsius) and excellent heat resistance, making it suitable for use as a refractory material in electric furnaces.

**Conclusion:** Statement C is **true**.

### Step 4: Analyze Statement D
**Statement D:** Milk of lime and lime water are two different solutions.

**Analysis:**
- This statement is true. Milk of lime is a suspension of calcium hydroxide (Ca(OH)2) in water, while lime water is a clear solution of calcium hydroxide in water. Therefore, they are indeed different.

**Conclusion:** Statement D is **true**.

### Final Conclusion
The correct statements regarding the oxides of alkali and alkaline earth metals are A, C, and D. Statement B is incorrect.

### Summary of Correct Statements:
- **A:** True
- **B:** False
- **C:** True
- **D:** True