Alkali metals are kept in kerosene oil. Which of the following reason (s) is /are correct regarding this statement?

Options

A. Due to high reactivity of alkali metal
B. Due to high ionisation enthalpy of alkali metals
C. Due to large size of alkali metals
D. Both (1) and (2)

Answer

To answer the question regarding why alkali metals are kept in kerosene oil, we can break down the reasoning into clear steps:

### Step-by-Step Solution:

1. **Understanding Alkali Metals**:
- Alkali metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). They are known for their high reactivity, especially with water and air.

**Hint**: Remember that alkali metals are in Group 1 of the periodic table and have one electron in their outermost shell.

2. **Reactivity with Air and Water**:
- Alkali metals react vigorously with water to produce hydroxides and hydrogen gas. For example, sodium reacts with water to form sodium hydroxide and hydrogen.
- They also react with oxygen in the air to form oxides. For instance, sodium reacts with oxygen to form sodium oxide.

**Hint**: Consider the chemical reactions that occur when alkali metals come into contact with water and air.

3. **Purpose of Kerosene Oil**:
- Kerosene oil is used to store alkali metals to prevent them from reacting with moisture in the air and water. By keeping them submerged in kerosene, we can avoid these dangerous reactions.

**Hint**: Think about how preventing exposure to air and water can help maintain the stability of reactive substances.

4. **Evaluating the Given Options**:
- **Option 1**: Due to high reactivity of alkali metals - This is correct.
- **Option 2**: Due to high ionization enthalpy of alkali metals - This is incorrect. Alkali metals actually have low ionization enthalpy, which contributes to their reactivity.
- **Option 3**: Due to large size of alkali metals - This is also incorrect. The large size does not directly relate to the need for kerosene oil.
- **Option 4**: Both 1 and 2 - This is incorrect since only option 1 is correct.

5. **Conclusion**:
- The correct reason for keeping alkali metals in kerosene oil is due to their high reactivity with air and water.

**Final Answer**: The correct option is **Option 1**: Due to high reactivity of alkali metals.