Which is that alloy in which copper is not present ?

Options

A. Copper
B. Duralumin
C. Brass
D. Solder

Explanation

To determine which alloy does not contain copper, we can analyze the given options one by one.

### Step-by-Step Solution:

1. **Understand the Definition of an Alloy**: An alloy is a homogeneous mixture of two or more metals, or a metal and a non-metal. Our goal is to identify an alloy that does not include copper.

2. **Evaluate Each Option**:
- **Option A: Copper**: This is not an alloy; it is a pure metal. Therefore, copper is present in this option. **(Incorrect)**
- **Option B: Duralumin**: Duralumin is an alloy made of aluminum, copper, magnesium, and manganese. Since it contains copper, this option is also **(Incorrect)**.
- **Option C: Brass**: Brass is an alloy composed of zinc and copper. As it contains copper, this option is **(Incorrect)**.
- **Option D: Solder**: Solder is an alloy made of tin and lead. It does not contain copper. Therefore, this option is **(Correct)**.

3. **Conclusion**: The alloy in which copper is not present is **Solder**.

### Final Answer:
The alloy in which copper is not present is **Solder**.

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