A solution with [H⁺] = 10⁻⁹ M has pH: MCQ with Answer and Explanation

Explanation:
V₂O₅ catalyzes the oxidation of SO₂ to SO₃ in the Contact process for sulfuric acid: 2SO₂ + O₂ ⇌ 2SO₃. Fe is used for ammonia (Haber). Pt-Rh gauze for nitric acid (Ostwald). Sodium hydroxide is made by chlor-alkali electrolysis, no catalyst needed. V₂O₅ is preferred over Pt because it is cheaper and less susceptible to poisoning by arsenic impurities.

Explanation:
Two or more substances combine to form a single product: N₂ + 3H₂ → 2NH₃. This is a combination (synthesis) reaction. Decomposition involves a single compound breaking down. Displacement: one element displaces another. Double displacement: exchange of ions. The Haber process for ammonia is also a redox and reversible reaction. Combination can be exothermic.

Explanation:
Bronze is Cu + Sn. Brass is Cu + Zn. Solder is Pb + Sn. Duralumin is Al + Cu + Mg. Bronze was one of the earliest alloys used by humans.