Which of the following processes is used to desalinate seawater?
a) Filtration
b) Reverse osmosis
c) Sedimentation
d) Chlorination
Answer: b) Reverse osmosis

What is the main cause of acid rain?
a) Carbon dioxide
b) Sulfur dioxide and nitrogen oxides
c) Methane
d) Ozone
Answer: b) Sulfur dioxide and nitrogen oxides

Which of the following contaminants is most harmful to aquatic life?
a) Phosphates
b) Sulfates
c) Chlorides
d) Nitrates
Answer: d) Nitrates

Water with a high concentration of dissolved oxygen is:
a) Polluted
b) Aerated
c) Distilled
d) Chlorinated
Answer: b) Aerated

Which of the following is a consequence of water pollution?
a) Increased biodiversity
b) Eutrophication
c) Reduced temperature of water bodies
d) Improved water quality
Answer: b) Eutrophication

Which is a characteristic of soft water?
a) High mineral content
b) Low mineral content
c) High pH
d) High hardness
Answer: b) Low mineral content

The presence of which ion indicates that water is hard?
a) Sodium
b) Potassium
c) Magnesium
d) Chloride
Answer: c) Magnesium

Which process is used to remove suspended solids from water?
a) Sedimentation
b) Filtration
c) Distillation
d) Evaporation
Answer: b) Filtration

The chemical used in water treatment to kill bacteria is:
a) Chlorine
b) Sodium hydroxide
c) Carbon dioxide
d) Ammonia
Answer: a) Chlorine

What is the primary effect of thermal pollution on water bodies?
a) Decrease in dissolved oxygen levels
b) Increase in water salinity
c) Decrease in water pH
d) Increase in nutrient levels
Answer: a) Decrease in dissolved oxygen levels