Which of these is an alloy?

Options

A. Brass
B. Nickel
C. Sodium
D. Hydrogen

Answer

To determine which of the given options is an alloy, we need to understand what an alloy is and analyze each option accordingly.

### Step-by-Step Solution:

1. **Definition of Alloy**: An alloy is a homogeneous mixture of two or more metals, or a metal and a non-metal. Alloys are usually created by melting the constituent metals together and allowing them to solidify.

2. **Analyzing the Options**:
- **Option A: Brass**: Brass is known to be an alloy made from copper and zinc. Since it is a mixture of two metals, it qualifies as an alloy.
- **Option B: Nickel**: Nickel is a pure metal and not a mixture of two or more metals. Therefore, it is not an alloy.
- **Option C: Sodium**: Sodium is also a pure metal and does not consist of a mixture of metals. Hence, it is not an alloy.
- **Option D: Hydrogen**: Hydrogen is a non-metal gas and does not fit the definition of an alloy.

3. **Conclusion**: The only option that qualifies as an alloy is **Brass** (Option A).

### Final Answer:
**Brass is an alloy.**

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