Aqua-regia contains conc. HCl and conc. `HNO_3` in the ratio of

Options

A. `1:3`
B. `3:1`
C. `1:3`
D. `1:5`

Explanation

To solve the question regarding the ratio of concentrated HCl to concentrated HNO3 in aqua regia, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Composition of Aqua Regia:**
Aqua regia is a highly corrosive mixture of acids that is known for its ability to dissolve noble metals like gold and platinum. It is composed of concentrated hydrochloric acid (HCl) and concentrated nitric acid (HNO3).

2. **Identify the Ratio of the Acids:**
It is known that aqua regia is prepared by mixing concentrated HCl and concentrated HNO3 in a specific ratio. The common ratio used in the preparation of aqua regia is 3:1.

3. **Express the Ratio:**
This means that for every 3 parts of concentrated HCl, there is 1 part of concentrated HNO3. Therefore, the ratio of concentrated HCl to concentrated HNO3 can be expressed as:
\[ \text{Ratio of HCl to HNO3} = 3:1 \]

4. **Conclusion:**
Thus, the ratio of concentrated HCl to concentrated HNO3 in aqua regia is 3:1.

### Final Answer:
The ratio of concentrated HCl to concentrated HNO3 in aqua regia is **3:1**.

---