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

Explanation:
Stainless steel contains at least 10.5% chromium, which reacts with oxygen to form a thin, adherent, transparent Cr₂O₃ layer (passive film) that prevents further oxidation of the underlying metal. Nickel enhances corrosion resistance and ductility. This self-healing oxide layer makes it 'stainless'. Unlike galvanization, the protection is not sacrificial but barrier-type from the inherent alloy composition.

Explanation:
NH₃ has a lone pair on nitrogen; it donates this pair to H⁺ to form a coordinate (dative) bond, where both electrons in the bond come from nitrogen. The resulting NH₄⁺ has four equivalent N-H bonds.

Explanation:
Chlorine leaves a residual in water, continuing to protect against recontamination in distribution pipes. Ozone and UV kill instantly but do not provide residual disinfection. Boiling is not used for municipal supply.