Aqua regia is a mixture of which of the following substances?

• A. Dilute hydrochloric acid and concentrated sulfuric acid
• B. Concentrated hydrochloric acid and concentrated nitric acid
• C. Concentrated hydrochloric acid and concentrated sulfuric acid
• D. Concentrated sulfuric acid and concentrated nitric acid

Answer: (B)

Verified step by step guidance

1. Understand that aqua regia is a special mixture used in chemistry to dissolve noble metals like gold and platinum, which are resistant to single acids.
2. Recall that aqua regia is composed of two concentrated acids mixed in a specific ratio to create a highly reactive solution.
3. Identify the acids involved: concentrated hydrochloric acid (HCl) and concentrated nitric acid (HNO\_3).
4. Recognize that the combination of these two acids produces reactive species such as nitrosyl chloride (NOCl) and chlorine gas (Cl\_2), which contribute to the dissolving power of aqua regia.
5. Conclude that the correct composition of aqua regia is concentrated hydrochloric acid and concentrated nitric acid.