Water and Its Importance

Water and its importance Worksheet-1

Multiple -Choice Question:

1. How much of the Earth’s surface is covered by water?

(a) 75%                (b) 50%                (c) 65%                (d) 81%

2. What percentage of the world’s water supply is fresh?

(a) 2.5%               (b) 7.5%               (c) 10%                (d) 20%

Water and its importance Worksheet-2

Multiple -Choice Question:

11. How the biological oxygen demand gets affected with the increased presence of organic matter in water?

(a) the oxygen demand decreases

(b) the oxygen demand increases

(c) the oxygen demand remains unchanged

(d) None of these

12. The presence of high coli form (the organisms which are found in the colon i.e. small intestine) counts in water indicate:

(a) phosphorus contamination

Water and its importance Worksheet-3

Multiple -Choice Question:

21. Which of the following is not a drawback of desalination plants?

(a) Desalinated water may cause cancer

(b) Energy intensive

(c) Negative impact on marine life

(d) Expensive