Mercury on heating with aqua regia gives

Options

A. `Hg(NO_(3))_(2)`
B. `HgCl_(2)`
C. `Hg(NO_(2))_(2)`
D. `Hg_(2)Cl_(2)`

Answer

To solve the question "Mercury on heating with aqua regia gives", we need to analyze the components involved and the reactions that occur.

### Step-by-Step Solution:

1. **Understand Aqua Regia Composition**:
Aqua regia is a mixture of hydrochloric acid (HCl) and nitric acid (HNO3) in a molar ratio of 3:1. It is known for its ability to dissolve noble metals like gold and platinum.

**Hint**: Remember the composition of aqua regia: 3 moles of HCl and 1 mole of HNO3.

2. **Identify the Reaction**:
When aqua regia is heated, the nitric acid (HNO3) reacts with hydrochloric acid (HCl) to produce nitrosyl chloride (NOCl) and water (H2O). The reaction can be summarized as:
\[ 3 \text{HCl} + \text{HNO}_3 \rightarrow \text{NOCl} + 2 \text{H}_2\text{O} \]

**Hint**: Focus on the products formed when HCl reacts with HNO3.

3. **Formation of Nascent Chlorine**:
The NOCl produced contains nascent chlorine, which is highly reactive. This nascent chlorine can further react with metals.

**Hint**: Remember that nascent chlorine is a powerful oxidizing agent.

4. **Reaction of Mercury with Nascent Chlorine**:
Mercury (Hg) reacts with the nascent chlorine (Cl) produced in the previous step. The reaction can be represented as:
\[ \text{Hg} + \text{Cl}_2 \rightarrow \text{HgCl}_2 \]
This means that mercury reacts with chlorine to form mercuric chloride (HgCl2).

**Hint**: Identify that mercury reacts with chlorine to form HgCl2.

5. **Conclusion**:
Therefore, when mercury is heated with aqua regia, it primarily forms mercuric chloride (HgCl2).

**Final Answer**: Mercury on heating with aqua regia gives **HgCl2**.

### Summary of the Answer:
The correct answer to the question is **HgCl2**.