The neutron was discovered by: MCQ with Answer and Explanation

Explanation:
Chlorination is a disinfection process. Chlorine reacts with water to form hypochlorous acid, which kills bacteria and viruses. It also provides residual protection in distribution pipes. Filtration removes particles; chlorine does not remove dissolved minerals or improve taste significantly; it can cause taste issues if excess.

Explanation:
Potassium (K) is an alkali metal placed at the very top of the reactivity series. It reacts violently with water and air, requiring storage in kerosene. Gold, silver, and copper are noble or less reactive metals placed at the bottom of the series, often found in the free state.

Explanation:
Arsenic (As) is a metalloid, showing properties of both metals and non-metals. It is in group 15, period 4. Sodium and calcium are metals. Oxygen is a non-metal. Metalloids: B, Si, Ge, As, Sb, Te. They are semiconductors and form amphoteric oxides.