When `AgNO_(3)` comes in contact with skin, it leaves a black stain. This is because of:

Options

A. `HNO_(3)` produced by hydrolysis of `AgNO_(3)`
B. `AgOH` produced by hydrolysis of `AgNO_(3)`
C. Its reduction of silver
D. Its oxidation to silver oxide

Answer

To solve the question of why `AgNO3` (silver nitrate) leaves a black stain when it comes in contact with skin, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding Silver Nitrate**:
- Silver nitrate (AgNO3) is a chemical compound that contains silver ions (Ag+) and nitrate ions (NO3-).

2. **Reaction with Skin**:
- When silver nitrate comes into contact with skin, it undergoes a chemical reaction. The silver ions (Ag+) in silver nitrate can be reduced to elemental silver (Ag).

3. **Formation of Black Stain**:
- The elemental silver that forms is in the form of microscopic particles. These particles are so small that they absorb light rather than reflecting it. This absorption of light gives the silver a black appearance instead of its usual metallic luster.

4. **Chemical Decomposition**:
- The decomposition reaction can be represented as:
\[ 2AgNO_3 \rightarrow 2Ag + 2NO_2 + O_2 \]
- In this reaction, silver nitrate decomposes to produce elemental silver, nitrogen dioxide (NO2), and oxygen (O2).

5. **Conclusion**:
- The black stain on the skin is due to the reduction of silver ions to elemental silver, which appears black due to its microscopic particle size.

### Final Answer:
The black stain left by `AgNO3` on the skin is due to the reduction of silver ions (Ag+) to elemental silver (Ag), which appears black because of its microscopic particle size.

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