Water Quality Parameters MCQ with answer and solution

Concept

Chemical compounds causing temporary water hardness

Formula

NONE

Step-by-step solution

1. Temporary hardness in water, also called carbonate hardness, can be removed by simple boiling. 2. It is caused by the presence of dissolved bicarbonates of calcium and magnesium. 3. Sulphates, chlorides, and nitrates of calcium and magnesium cause permanent hardness. Answer: A

Explanation

Temporary hardness in water is caused by dissolved bicarbonates of calcium and magnesium. It is called temporary because these bicarbonate salts decompose and precipitate out as insoluble carbonates simply by boiling the water. In contrast, sulfates, chlorides, and nitrates of calcium and magnesium cause permanent hardness.

Why the other options are wrong

B) Sulphates of calcium and magnesium cause permanent hardness in water. C) Chlorides of calcium and magnesium cause permanent hardness in water. D) Nitrates of calcium and magnesium cause permanent hardness in water.

Shortcut

Temporary hardness is caused by Bicarbonates (TB: Temporary = Bicarbonates).

Common mistake

Confusing temporary hardness caused by bicarbonates with permanent hardness caused by sulphates, chlorides, or nitrates.