ASMO Science Olympiad 2016 — Level 2 (Years 5 & 6) — Contest Question 20

Question 20

Many countries river water is used for washing of clothes. The river water is not safe for drinking. Why is it not safe for drinking?

1. Because river water contains dissolved salts
2. Because river water contain soap from washing clothes
3. Because river water contain small particles of sand
4. Because river water may contain harmful bacteria