Hydrogen combines with other elements by

Options

A. losing an electron
B. gaining an electron
C. sharing an electron
D. losing, gaining and sharing of an electron

Explanation

To answer the question "Hydrogen combines with other elements by," we need to analyze the different ways hydrogen can bond with other elements. The options provided suggest various mechanisms of bonding: losing an electron, gaining an electron, sharing an electron, or a combination of all these methods.

### Step-by-Step Solution:

1. **Understanding Hydrogen's Electron Configuration**:
- Hydrogen has one electron in its outer shell (1s¹). This means it can either lose this electron, gain another one, or share it to achieve a stable electronic configuration.

2. **Losing an Electron**:
- When hydrogen loses an electron, it forms a cation (H⁺). A good example of this is hydrogen fluoride (HF).
- In HF, hydrogen donates its single electron to fluorine, which needs one more electron to complete its octet. This results in the formation of a bond where hydrogen effectively loses its electron.

3. **Gaining an Electron**:
- Hydrogen can also gain an electron to form an anion (H⁻). A classic example is sodium hydride (NaH).
- In this case, sodium (Na) has one electron in its outer shell (3s¹) and is willing to lose it. Hydrogen accepts this electron, resulting in the formation of the hydride ion (H⁻) and a stable ionic compound NaH.

4. **Sharing an Electron**:
- Hydrogen can also share its electron with another atom to form covalent bonds. A prominent example is ammonia (NH₃).
- In NH₃, nitrogen shares its electrons with three hydrogen atoms. Each hydrogen atom shares its single electron with nitrogen, allowing nitrogen to complete its octet while hydrogen achieves a stable configuration.

5. **Conclusion**:
- Hydrogen can combine with other elements by losing an electron, gaining an electron, or sharing an electron. Therefore, the correct answer is that hydrogen combines with other elements by all of the above methods.

### Final Answer:
Hydrogen combines with other elements by losing, gaining, and sharing electrons.