Which of the following element is a bad conductor of electricity?

Options

A. Bi
B. Na
C. K
D. He

Explanation

To determine which of the following elements is a bad conductor of electricity, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Conductors and Insulators**:
- Conductors are materials that allow electricity to flow through them easily. Metals are generally good conductors.
- Insulators (or bad conductors) are materials that do not allow electricity to flow easily. Non-metals are typically considered bad conductors.

2. **Identify the Elements**:
- The elements given in the question are Bismuth (Bi), Sodium (Na), Potassium (K), and Helium (He).

3. **Classify Each Element**:
- **Bismuth (Bi)**: This is a metal and is a good conductor of electricity.
- **Sodium (Na)**: This is also a metal and is a good conductor of electricity.
- **Potassium (K)**: This is another metal and is a good conductor of electricity.
- **Helium (He)**: This is a non-metal (specifically a noble gas) and is considered a bad conductor of electricity.

4. **Conclusion**:
- Among the given options, Helium (He) is the only element that is a bad conductor of electricity.

### Final Answer:
The element that is a bad conductor of electricity is **Helium (He)**.

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