The correct statement among the following is/are

Options

A. the electrical conductivity of pure semiconductor increases by doping
B. the electrical conductivity of pure semiconductor decreases by doping
C. there is no effect of doping on the electrical conductivity of semiconductor
D. electrical conductivity of pure semiconductor may increase or decrease on doping

Answer

To solve the question regarding the electrical conductivity of semiconductors and the effects of doping, we can analyze each statement provided in the options.

### Step-by-Step Solution:

1. **Understanding Semiconductors**:
- Semiconductors are materials that have electrical conductivity between that of conductors (like metals) and insulators (like plastics). Common examples include silicon and germanium.

**Hint**: Recall the classification of materials based on their electrical conductivity: conductors, semiconductors, and insulators.

2. **Effect of Doping**:
- Doping is the process of adding impurities to a semiconductor to change its electrical properties. This is typically done by introducing elements from Group III (like aluminum) or Group V (like phosphorus) of the periodic table.
- Group III elements have three valence electrons, while Group V elements have five. When these elements are added to a pure semiconductor, they create either "holes" (from Group III) or extra electrons (from Group V), which increases the number of charge carriers.

**Hint**: Remember that doping introduces additional charge carriers, which enhances conductivity.

3. **Analyzing the Options**:
- **Option 1**: "Electrical conductivity of pure semiconductor increases by doping."
- This statement is **correct** because doping increases the number of charge carriers, thus increasing conductivity.

- **Option 2**: "Electrical conductivity decreases."
- This statement is **incorrect**. Doping does not decrease conductivity; it increases it.

- **Option 3**: "There is no effect of doping."
- This statement is **incorrect**. Doping has a significant effect on the conductivity of semiconductors.

- **Option 4**: "The electrical conductivity of a pure semiconductor may increase or decrease on doping."
- This statement is also **incorrect**. Doping consistently increases conductivity; it does not cause a decrease.

4. **Conclusion**:
- The only correct statement among the options is Option 1: "Electrical conductivity of pure semiconductor increases by doping."

### Final Answer:
The correct statement is: **Electrical conductivity of pure semiconductor increases by doping.**