Which of the following reactions is a double displacement reaction? MCQ with Answer and Explanation

Explanation:
Sulphuric acid (H₂SO₄) is historically called oil of vitriol because it was prepared by distilling green vitriol (ferrous sulfate heptahydrate). It is a dense, oily liquid. Nitric acid is aqua fortis, hydrochloric acid was called muriatic acid or spirit of salt. Sulphuric acid is the king of chemicals due to its widespread use in industries like fertilizer, petroleum refining, and chemical synthesis.

Explanation:
A catalyst lowers the activation energy for both the forward and reverse reactions by the same amount. Therefore, it increases the rates of both reactions equally, allowing the system to reach equilibrium faster, but without changing the final equilibrium concentrations (yield). Both statements are correct and R explains A.

Explanation:
A buffer solution maintains a relatively constant pH when small amounts of strong acid or base are added. However, it is typically composed of a weak acid and its conjugate base (or a weak base and its conjugate acid). A strong acid completely dissociates and cannot form a buffer system. Thus, only statement 1 is correct.