Multiple choice

Which of the following is added to purify water in big cities?

  1. Calcium carboante

  2. Sodium

  3. Lime

  4. Chlorine

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Chlorine effectively kills bacteria and other pathogens in water supplies. It's the most common disinfectant for municipal water treatment because it provides residual protection throughout the distribution system. Lime is sometimes used for pH adjustment but not as the primary disinfectant.