Which of the following groups represents the hydrides?

Options

A. `NaH,KH,CaH_(2)`
B. `NaH,SiH_(2),CaH_(2)`
C. `NH_(3),BH_(3),AlH_(3)`
D. None of these

Explanation

To determine which group represents the hydrides, we need to understand what hydrides are and how they are formed.

### Step-by-Step Solution:

1. **Definition of Hydrides**: Hydrides are compounds formed when hydrogen (H) bonds with electropositive metals. In these compounds, hydrogen typically acts as a hydride ion (H⁻).

2. **Formation of Hydrides**: The formation of hydrides occurs when an electropositive metal reacts with hydrogen gas. For example, when sodium (Na) reacts with hydrogen gas (H₂), it forms sodium hydride (NaH).

3. **Identifying Electropositive Metals**: To identify which groups represent hydrides, we need to focus on the groups of metals that are electropositive. Electropositive metals are typically found in the leftmost sections of the periodic table.

4. **Periodic Table Trends**: As we move from left to right across the periodic table, the electropositive character of elements decreases. This means that elements on the left (such as alkali metals and alkaline earth metals) are more electropositive and more likely to form hydrides.

5. **Groups of Interest**: The first group of the periodic table is the alkali metals (e.g., lithium, sodium, potassium), and the second group is the alkaline earth metals (e.g., magnesium, calcium). Both of these groups contain metals that can form hydrides.

6. **Conclusion**: Therefore, the group that represents hydrides consists of alkali metals and alkaline earth metals, as they can readily form hydrides with hydrogen.

### Final Answer:
The group that represents the hydrides is the **alkali metals (Group 1)** and **alkaline earth metals (Group 2)**.

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