Which of the following is NOT a method to purify water? MCQ with Answer and Explanation

Explanation:
Petroleum (crude oil) and natural gas are formed from the remains of tiny marine organisms (plankton) that settled on the seabed, buried under sediment, and transformed by heat and pressure over millions of years. Coal is formed from terrestrial plant material in swampy conditions. Biogas is produced by anaerobic decomposition of organic waste. Charcoal is produced by destructive distillation of wood.

Explanation:
The Solvay process (or ammonia-soda process) is the major industrial process for the production of sodium carbonate (soda ash, Na2CO3). It uses brine (NaCl) and limestone (CaCO3) as raw materials, with ammonia acting as an intermediate that is recovered and recycled.

Explanation:
Electrolysis of water decomposes it into hydrogen and oxygen, not purification. Boiling kills microbes, filtration removes particulate matter, chlorination disinfects. Other methods: UV treatment, ozonation, reverse osmosis, distillation. Electrolysis is a chemical decomposition technique.