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

Explanation:
UV radiation releases chlorine atoms from CFCs; Cl catalytically decomposes O₃: Cl + O₃ → ClO + O₂; ClO + O → Cl + O₂. One Cl atom can destroy thousands of ozone molecules.

Explanation:
Sodium (alkali metal) reacts violently with cold water: 2Na + 2H₂O → 2NaOH + H₂ + heat. Copper and iron do not react with cold water; iron reacts with steam. Zinc also reacts with steam. Reactivity with water increases down Group 1.

Explanation:
Azotobacter is a free-living aerobic bacterium that fixes atmospheric nitrogen in the soil, making it available to non-leguminous crops. Rhizobium is symbiotic and specific to legumes. Nitrobacter and Nitrosomonas are involved in nitrification (converting ammonia to nitrites/nitrates), not nitrogen fixation.