Sulphuric acid is used in the preparation of which of the following? MCQ with Answer and Explanation

Explanation:
Silver and gold are noble metals and occur in the free (native) state in nature because they are extremely unreactive (least reactive), not highly reactive. They do not readily combine with oxygen, moisture, or acids. Thus, A is true, but R is false.

Explanation:
At higher temperatures, the rate of diffusion increases because the kinetic energy of the gas molecules (food aroma) increases. Thus, the smell of hot food diffuses faster and reaches further. Both statements are correct, and the increased kinetic energy perfectly explains the enhanced diffusion rate observed in the assertion.

Explanation:
Roasting: 2ZnS + 3O₂ → 2ZnO + 2SO₂. The oxide is then reduced with coke at high temperature: ZnO + C → Zn + CO. Alternatively, it can be leached with H₂SO₄ and electrolyzed.