Test: Water - 1 - JAMB MCQ

Water (H₂O) is formed by the combination of two parts hydrogen (H) and one part oxygen (O) by volume, which corresponds to approximately 66.7% hydrogen and 33.3% oxygen.

Atmospheric gases dissolved in water, particularly oxygen, play a vital role in supporting aquatic life by providing the necessary oxygen for respiration.

Hard water is characterized by a high mineral content, usually containing dissolved calcium and magnesium ions. Due to the presence of these ions, it causes difficulties in lathering with soap and can leave mineral deposits.

Temporary hardness is caused by the presence of dissolved bicarbonate ions in water, which can be removed by boiling. Boiling causes the bicarbonate ions to decompose, forming insoluble carbonate precipitates that can be removed.

Ion exchange is a commonly used method to soften hard water. It involves passing hard water through a resin bed that exchanges calcium and magnesium ions with sodium or potassium ions, thus reducing the hardness of the water.

Chlorination is a process involved in the treatment of water for town supply. It involves adding chlorine or its compounds to the water to disinfect and kill harmful microorganisms.

Efflorescence is the phenomenon in which a substance loses water of crystallization to the surrounding environment, resulting in the formation of a powdery deposit on the surface of the substance.

Sodium chloride (table salt) is hygroscopic, meaning it has the ability to absorb moisture from the atmosphere. It readily absorbs water vapor, causing it to clump together.

Deliquescence is the property of a substance to absorb water vapor from the atmosphere, forming a liquid solution. It occurs when the substance has a higher affinity for water than the vapor pressure of the surrounding air.

Calcium sulfate (gypsum) exhibits water of crystallization and forms crystals with two water molecules (CaSO₄·2H₂O) within its structure. These water molecules are chemically bound to the crystal lattice.