Which of the following is a representative element ?

Options

A. Zn
B. Sr
C. Cu
D. Fe

Answer

To determine which of the following is a representative element, we need to understand what representative elements are and how to identify them based on their electronic configurations.

### Step-by-Step Solution:

1. **Define Representative Elements**:
- Representative elements are those found in the s and p blocks of the periodic table. They include groups 1 and 2 (s block) and groups 13 to 18 (p block).

2. **Identify the Blocks**:
- **s Block**: Contains elements where the last electron enters the s orbital (groups 1 and 2).
- **p Block**: Contains elements where the last electron enters the p orbital (groups 13 to 18).
- **d Block**: Contains transition metals where the last electron enters the d orbital (groups 3 to 12).

3. **Determine the Electronic Configuration**:
- To find out if an element is a representative element, we need to look at its electronic configuration.
- For example, for Strontium (Sr), which has an atomic number of 38, the electronic configuration is [Kr] 5s². The last electron is in the s orbital, indicating it is an s block element and thus a representative element.

4. **Analyze Other Elements**:
- **Zinc (Zn)**: Atomic number 30, electronic configuration is [Ar] 3d¹⁰ 4s². The last electron is in the d orbital, making it a d block element (not representative).
- **Copper (Cu)**: Atomic number 29, electronic configuration is [Ar] 3d¹⁰ 4s¹. The last electron is in the d orbital, making it a d block element (not representative).
- **Iron (Fe)**: Atomic number 26, electronic configuration is [Ar] 3d⁶ 4s². The last electron is in the d orbital, making it a d block element (not representative).

5. **Conclusion**:
- Among the elements analyzed, Strontium (Sr) is the only representative element as it belongs to the s block.

### Final Answer:
Strontium (Sr) is a representative element.

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