`H^(Theta)` always act as

Options

A. Nucleophile
B. Base
C. Electrophile
D. Ambiphile

Answer

To solve the question "H⁻ always acts as", we need to analyze the properties of the H⁻ ion, also known as the hydride ion, and compare it with the given options: nucleophile, base, electrophile, and ambiphile.

### Step-by-Step Solution:

1. **Understanding H⁻ (Hydride Ion)**:
- The hydride ion (H⁻) consists of one proton and two electrons. It is negatively charged, which indicates that it has an excess of electrons.

2. **Analyzing the Options**:
- **Nucleophile**: A nucleophile is a species that donates an electron pair to form a chemical bond. H⁻ can act as a nucleophile because it has extra electrons that can be donated.
- **Base**: A base is a substance that can accept protons (H⁺). H⁻ can accept a proton to form hydrogen gas (H₂), which means it acts as a strong base.
- **Electrophile**: An electrophile is a species that accepts electrons. H⁻ does not accept electrons; instead, it donates them, so it does not act as an electrophile.
- **Ambiphile**: An ambiphile can act as both a nucleophile and an electrophile. While H⁻ can act as a nucleophile, it does not accept electrons, so it does not fully fit the definition of an ambiphile.

3. **Conclusion**:
- Based on the analysis, H⁻ primarily acts as a base because it readily accepts protons (H⁺) to form hydrogen gas (H₂). While it can also act as a nucleophile, its most significant and defining behavior is that of a base.

### Final Answer:
H⁻ always acts as a **base**.