AP ECET CHEMISTRY Multiple Choice Questions (MCQs)

76. What is the main cause of hardness in water?

• a) Presence of dissolved salts
• b) High temperature
• c) High pH level
• d) Presence of microorganisms

Answer: a) Presence of dissolved salts

77. Which of the following is a type of hardness in water?

• a) Temporary hardness
• b) Permanent hardness
• c) Both a and b
• d) None of the above

Answer: c) Both a and b

78. Which of the following substances primarily causes permanent hardness in water?

• a) Calcium bicarbonate
• b) Magnesium sulfate
• c) Sodium chloride
• d) Potassium carbonate

Answer: b) Magnesium sulfate

79. Which of the following methods is used for softening hard water?

• a) Boiling
• b) Filtration
• c) Ion-exchange process
• d) Freezing

Answer: c) Ion-exchange process

80. The unit of hardness in water is generally measured in:

• a) PPM (parts per million)
• b) Liters per meter
• c) Milligrams per liter
• d) Degrees Celsius

Answer: c) Milligrams per liter

81. Which of the following is not a disadvantage of hard water?

• a) Scaling in pipes
• b) Reduced soap efficiency
• c) Better taste
• d) Damage to water-heating appliances

Answer: c) Better taste

82. Which ion is responsible for the temporary hardness of water?

• a) Calcium ions
• b) Magnesium ions
• c) Bicarbonate ions
• d) Sulfate ions

Answer: c) Bicarbonate ions

83. What is the degree of hardness of water measured in?

• a) moles per liter
• b) mg/L as calcium carbonate (CaCO3)
• c) moles per cubic meter
• d) grams per liter

Answer: b) mg/L as calcium carbonate (CaCO3)

84. The permutit process of water softening is also known as:

• a) Reverse osmosis
• b) Zeolite softening
• c) Ion-exchange
• d) Chlorination

Answer: b) Zeolite softening

85. Which of the following is an example of a method for treating drinking water at the municipal level?

• a) Chlorination
• b) Ozonation
• c) Filtration
• d) All of the above

Answer: d) All of the above

86. The hardness of water is primarily caused by which of the following compounds?

• a) Calcium carbonate
• b) Sodium chloride
• c) Potassium nitrate
• d) Ammonium sulfate

Answer: a) Calcium carbonate

87. Which of the following is a common characteristic of soft water?

• a) High levels of calcium and magnesium
• b) High levels of sodium ions
• c) Low levels of calcium and magnesium
• d) High chlorine content

Answer: c) Low levels of calcium and magnesium

88. Which of the following is a method for removing hardness in water using an ion-exchange process?

• a) Reverse osmosis
• b) Softening through zeolite
• c) Chemical precipitation
• d) Filtration

Answer: b) Softening through zeolite

89. What is the typical hardness of drinking water?

• a) 0 to 50 mg/L
• b) 100 to 200 mg/L
• c) 250 to 500 mg/L
• d) 500 to 1000 mg/L

Answer: b) 100 to 200 mg/L

90. Which of the following is not involved in the municipal treatment of drinking water?

• a) Sedimentation
• b) Chlorination
• c) Reverse osmosis
• d) Filtration

Answer: c) Reverse osmosis