Phenol is highly corrosive substance , but its 0.2 percent solution is used as .

Options

A. antibiotic
B. antiseptic
C. disinfectant
D. antihistamine

Answer

### Step-by-Step Solution:

1. **Understanding Phenol**:
- Phenol is a chemical compound with the formula C6H5OH. It consists of a benzene ring (C6H5) with a hydroxyl group (OH) attached to it.
- It is known for its corrosive properties in concentrated forms.

2. **Concentration of Phenol**:
- The question specifies a 0.2% solution of phenol. This means that in 100 mL of solution, there are 0.2 grams of phenol.

3. **Antimicrobial Properties**:
- Research has shown that phenol possesses antimicrobial properties, making it effective against various microorganisms. This makes it useful in medical and cleaning applications.

4. **Uses of 0.2% Phenol Solution**:
- A 0.2% solution of phenol is primarily used as an **antiseptic**. Antiseptics are substances that prevent the growth of disease-causing microorganisms on living tissues.
- It can be applied to cuts, wounds, or skin irritations to prevent infection.

5. **Comparison with Higher Concentrations**:
- While a 0.2% solution is used as an antiseptic, higher concentrations (around 1%) are used as disinfectants for cleaning surfaces and surgical instruments to eliminate bacteria.

6. **Conclusion**:
- Therefore, the correct answer to the question is that a 0.2% solution of phenol is used as an **antiseptic**.