71. The term “ppm” stands for:
A) Parts per million
B) Parts per meter
C) Power per mass
D) None
Answer: A
72. Which is a heavy metal pollutant?
A) Mercury
B) Oxygen
C) Nitrogen
D) Hydrogen
Answer: A
73. Mercury poisoning causes:
A) Minamata disease
B) Asthma
C) Flu
D) Fever
Answer: A
74. Which gas is released during decomposition?
A) Methane
B) Oxygen
C) Nitrogen
D) Hydrogen
Answer: A
75. The major source of carbon monoxide is:
A) Incomplete combustion
B) Plants
C) Water
D) Soil
Answer: A
76. Which pollutant affects hemoglobin?
A) CO
B) O₂
C) N₂
D) H₂
Answer: A
77. The safe drinking water pH range is:
A) 3–5
B) 6.5–8.5
C) 9–11
D) 12–14
Answer: B
78. Which process removes hardness of water?
A) Boiling
B) Filtration
C) Distillation
D) All
Answer: D
79. Hard water contains:
A) Na⁺
B) Ca²⁺ and Mg²⁺
C) K⁺
D) Cl⁻
Answer: B
80. Which gas is colorless and odorless but toxic?
A) CO
B) CO₂
C) O₂
D) N₂
Answer: A