Which of the following metals reacts with cold water? MCQ with Answer and Explanation

Explanation:
Ammonium ion (NH₄⁺) contains a coordinate bond: NH₃ donates its lone pair of electrons to H⁺ to form a covalent bond where both electrons come from nitrogen. NaCl is ionic, NH₃ has ordinary covalent bonds, Cl₂ has a nonpolar covalent bond. In NH₄⁺, all four N–H bonds are equivalent after formation. Coordinate bond is also called dative bond and is common in complex ions like [Cu(NH₃)₄]²⁺.

Explanation:
Carbon-14 (half-life ~5730 years) is used to determine the age of archaeological and geological organic samples up to ~50,000 years. Cobalt-60 for cancer; Am-241 for smoke detectors.

Explanation:
Bleaching powder is calcium oxychloride, CaOCl₂, made by passing chlorine gas over dry slaked lime (Ca(OH)₂): Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O. Quicklime is CaO, limestone is CaCO₃, gypsum is CaSO₄·2H₂O. Bleaching powder is used for bleaching cotton and paper, disinfecting water, and as an oxidizing agent. It releases chlorine on exposure to air or acids.