Which salt is formed when hydrochloric acid reacts with sodium hydroxide? MCQ with Answer and Explanation

Explanation:
Fraction remaining = (1/2)^n = 1/16 => n = 4 half-lives. Time = n × half-life = 4 × 4 = 16 years. After 1 half-life: 1/2, 2: 1/4, 3: 1/8, 4: 1/16. Radioactive decay is exponential. So after 16 years, only 1/16th of original radioactive atoms remain.

Explanation:
Ernest Rutherford, along with his students Geiger and Marsden, conducted the famous gold foil experiment in 1911. By observing that a few alpha particles bounced back, he concluded that the atom has a small, dense, positively charged center called the nucleus.

Explanation:
Chlorination is the disinfection of water using chlorine or chlorine compounds to destroy pathogenic microorganisms. Chlorine reacts with water forming hypochlorous acid (HOCl) which is a strong germicide. Ozonation uses ozone; distillation involves boiling and condensation. Filtration removes particulate matter but not all microorganisms. Chlorination is cost-effective and provides residual protection, though it may produce trihalomethanes as by-products.