Which gas diffuses fastest under identical conditions? MCQ with Answer and Explanation

Explanation:
Hydrogenation of alkenes (addition of H₂ across double bond) is catalyzed by finely divided metals like nickel, platinum, or palladium. These adsorb H₂ and the unsaturated compound, facilitating reaction. V₂O₅ is for oxidation (Contact), MnO₂ for H₂O₂ decomposition, Fe for Haber process. Nickel is the most common industrial catalyst for hydrogenation.

Explanation:
NaOH is a strong base; it dissociates to give OH⁻ ions, making the solution basic (pH >7). Bases turn red litmus blue. Acids turn blue litmus red.

Explanation:
SO₂ from burning coal and NOₓ from vehicles form H₂SO₄ and HNO₃ in rain. CO₂ forms weak carbonic acid (normal rain pH ~5.6). Ammonia is basic and neutralizes acidity.