Aqua regia, which can dissolve gold and platinum, is a mixture of: MCQ with Answer and Explanation

Question

Share Report Error

Aqua regia, which can dissolve gold and platinum, is a mixture of:

A. HF and HCl

B. HCl and H₂SO₄

C. HCl and HNO₃ in ratio 3:1

D. HNO₃ and H₂SO₄

Answer: Option C

Solution (By JKSSB Mock Tests)

Aqua regia (royal water) is a 3:1 mixture by volume of concentrated HCl and HNO₃. It generates nascent chlorine and nitrosyl chloride, which oxidize gold and platinum to soluble chloro complexes (e.g., HAuCl₄). Neither acid alone can dissolve these noble metals. Used for cleaning glassware and in etching. Must be prepared fresh and handled with extreme care.

This question belongs to: Science chemistry

Request complete Subject PDF

Discuss this Question (0)

No comments yet. Be the first to start the discussion!

Practice More chemistry Questions

Question #1

Share Report

Assertion (A): Silver chloride turns grey when kept in sunlight. Reason (R): Silver chloride undergoes a decomposition reaction by sunlight.

A. A is false but R is true.

B. A is true but R is false.

C. Both A and R are true and R is the correct explanation of A.

D. Both A and R are true but R is NOT the correct explanation of A.

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
When exposed to sunlight, silver chloride (AgCl) undergoes photolytic decomposition to form silver metal (which is grey) and chlorine gas. The equation is 2AgCl(s) + sunlight → 2Ag(s) + Cl₂(g). Both statements are correct, and the decomposition reaction perfectly explains the color change observed.

This question belongs to: Science chemistry

Question #2

Share Report

Which change is exothermic?

A. Combustion of methane

B. Evaporation of water

C. Sublimation of camphor

D. Melting of ice

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Combustion of methane (CH₄ + 2O₂ → CO₂ + 2H₂O + heat) is an exothermic reaction, releasing heat to surroundings. Melting, evaporation, and sublimation are endothermic phase changes requiring heat absorption to overcome intermolecular forces. Exothermic reactions: burning, respiration, neutralization (usually), condensation, freezing. Endothermic: photosynthesis, cooking, melting, boiling.

This question belongs to: Science chemistry

Question #3

Share Report

In the redox reaction Zn + CuSO₄ → ZnSO₄ + Cu, the reducing agent is:

A. Cu

B. CuSO₄

C. ZnSO₄

D. Zn

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Zinc loses electrons (Zn → Zn²⁺ + 2e⁻) and thus is oxidized. The substance that gets oxidized is the reducing agent. Copper sulfate is reduced (Cu²⁺ to Cu) and is the oxidizing agent. The reducing agent donates electrons.

This question belongs to: Science chemistry

Explore All chemistry MCQs