In preparation of which of the following, dihydrogen is not used?

Options

A. Vanaspati Ghee
B. Metal hydrides
C. Sodium bicarbonate
D. Hydrogen chloride

Explanation

To determine in which of the following compounds dihydrogen (H₂) is not used in its preparation, we will analyze each option provided:

1. **Vanaspati Ghee**:
- Vanaspati ghee is produced through the hydrogenation of vegetable oils. In this process, dihydrogen gas is used to convert unsaturated fats into saturated fats, resulting in the solid fat known as vanaspati. Thus, dihydrogen is used in the preparation of vanaspati ghee.

2. **Metal Hydrides**:
- Metal hydrides are compounds formed between metals and hydrogen. Dihydrogen is typically used to react with metals to form metal hydrides. Therefore, dihydrogen is used in the preparation of metal hydrides.

3. **Sodium Bicarbonate (NaHCO₃)**:
- Sodium bicarbonate is prepared through the reaction of ammonia (NH₃), carbon dioxide (CO₂), and water (H₂O). The overall reaction does not involve dihydrogen. Instead, it involves the formation of ammonium bicarbonate (NH₄HCO₃) followed by its reaction with sodium chloride (NaCl) to produce sodium bicarbonate. Thus, dihydrogen is not used in the preparation of sodium bicarbonate.

4. **Hydrogen Chloride (HCl)**:
- Hydrogen chloride can be produced by the direct combination of hydrogen gas and chlorine gas. Therefore, dihydrogen is used in the preparation of hydrogen chloride.

Based on the analysis above, the correct answer is:

**Sodium Bicarbonate** is the compound in which dihydrogen is not used in its preparation.

### Summary of Steps:
1. Analyze the preparation of Vanaspati Ghee - dihydrogen is used.
2. Analyze the preparation of Metal Hydrides - dihydrogen is used.
3. Analyze the preparation of Sodium Bicarbonate - dihydrogen is not used.
4. Analyze the preparation of Hydrogen Chloride - dihydrogen is used.
5. Conclude that Sodium Bicarbonate is the correct answer.