A catalyst that slows down a reaction is known as: MCQ with Answer and Explanation

Explanation:
Ostwald process: NH₃ oxidized to NO over Pt-Rh catalyst at 800°C. Fe for Haber; Ni for hydrogenation; V₂O₅ for SO₂ oxidation.

Explanation:
Carbon dioxide (CO₂) is the primary greenhouse gas emitted from the burning of fossil fuels (coal, oil, natural gas). It traps heat in the Earth's atmosphere, leading to global warming. Oxygen, nitrogen, and hydrogen do not absorb infrared radiation and thus do not contribute to the greenhouse effect.

Explanation:
Distillation separates a mixture of two or more miscible liquids with different boiling points. The liquid with the lower boiling point vaporizes first, is condensed, and collected separately. Fractional distillation is used when the boiling point difference is less than 25 K. Simple distillation works for larger differences. Filtration separates solids from liquids; sublimation separates sublimable solids; chromatography separates dissolved substances based on differential adsorption.