Natural gas mainly contains: MCQ with Answer and Explanation

Explanation:
Electrolysis of water splits it into hydrogen and oxygen, it is not a purification method but a decomposition. Reverse osmosis uses semipermeable membrane to remove ions and impurities. UV irradiation kills microorganisms. Distillation boils water and condenses steam, removing non-volatile impurities. Other methods: filtration, chlorination, ozonation, boiling.

Explanation:
Hydrochloric acid (HCl) is a strong acid because it completely dissociates into H⁺ and Cl⁻ ions in aqueous solution. Acetic, citric, and carbonic acids are weak acids as they only partially dissociate in water, establishing an equilibrium between the unionized molecules and their ions.

Explanation:
Rusting is an electrochemical process requiring both oxygen and water (moisture). The overall reaction: 4Fe + 3O₂ + 2xH₂O → 2Fe₂O₃·xH₂O. In the absence of either, rusting does not occur. Salt accelerates rusting by increasing conductivity. Prevention methods include painting, greasing, galvanization, and cathodic protection. Rust is hydrated iron(III) oxide, a reddish-brown flaky substance, not protective.