50 MCQs on Water and Its Treatment (With Answers)

Water is often called the universal solvent because it:

• Dissolves only organic compounds

• Dissolves a large variety of substances

• Does not react with chemicals

• Has high boiling point

Which of the following is NOT a property of pure water?

• A. Colourless

• B. Odourless

• C. Toxic

• D. Renewable

Water used in industrial processes is considered an important:

• Chemical reagent

• Engineering material

• Catalyst

• Fuel

Which of the following is a source of freshwater?

• Oceans

• Rivers

• Seas

• Saline lakes

Which of the following is a suspended impurity in water?

• Carbon dioxide

• Clay

• Calcium carbonate

• Sodium chloride

Dissolved gases in water include:

• Oxygen

• Carbon dioxide

• Both A and B

• Nitrogen only

Which of the following is a colloidal impurity in water?

• Silica

• Sand

• Clay particles

• Sodium chloride

Hardness of water is mainly caused by salts of:

• Sodium and potassium

• Calcium and magnesium

• Iron and copper

• Zinc and aluminium

Hard water does not form lather with soap because:

• Soap reacts with Ca2+ and Mg2+ ions

• Soap dissolves poorly

• Water contains oil

• Soap evaporates

The property of water that prevents lather formation with soap is called:

• Salinity

• Hardness

• Acidity

• Alkalinity