`SnO_2` is insoluble in

Options

A. conc. HCI
B. hot HNO3,
C. aqua regia
D. All of the above.

Answer

To determine the solubility of \( \text{SnO}_2 \) (tin dioxide) in various acids, we can analyze each option provided:

### Step 1: Understand the nature of \( \text{SnO}_2 \)
- \( \text{SnO}_2 \) is a metal oxide, specifically an amphoteric oxide. This means it can react with both acids and bases, but it is generally insoluble in many common acids.

### Step 2: Analyze the options
1. **Concentrated Hydrochloric Acid (HCl)**:
- \( \text{SnO}_2 \) does not dissolve in concentrated hydrochloric acid. This is because it is not reactive enough with strong acids to form soluble tin salts.

2. **Hot Concentrated Nitric Acid (HNO3)**:
- Similarly, \( \text{SnO}_2 \) is also insoluble in hot concentrated nitric acid. While nitric acid can oxidize some metals, tin dioxide remains insoluble.

3. **Aqua Regia**:
- Aqua regia is a mixture of concentrated hydrochloric acid and concentrated nitric acid (in a 3:1 ratio). Despite its strong oxidizing properties, \( \text{SnO}_2 \) does not dissolve in aqua regia either.

### Step 3: Conclusion
- Since \( \text{SnO}_2 \) is insoluble in all the acids mentioned (concentrated HCl, hot concentrated HNO3, and aqua regia), the correct answer is that \( \text{SnO}_2 \) is insoluble in **all of the above**.

### Final Answer:
- \( \text{SnO}_2 \) is insoluble in all of the above options.

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