The chemicals released in water during industrial processes include arsenic, lead and fluorides. They contaminate the water and cause toxicity.

Water that is fit for drinking is called potable water.

Typhoid is a water-borne disease.

Excessive growth of algae gives a green appearance to ponds. It is caused by excessive quantities of chemicals which act as a source of nutrients.

Acid rain corrodes marbles of a monument. This phenomenon is called marble cancer.

CNG is a cleaner fuel. It is being promoted in cities with high air pollution. CNG combustion produces fewer undesirable gases than the other fuels. It is safer than other fuels in the event of a spill because natural gas is lighter than air and disperses quickly when released. 

Leakage of CFCs from refrigerators and air conditioners causes air pollution. CFCs result in the depletion of ozone air.

Ozone gets converted into oxygen due to the action of CFCs in the environment and results in the depletion of the protective ozone layer of Earth.

The average composition of dry air is N₂ = 75%, O₂ = 20.95%, Argon = 0.93%, CO₂ = 0.03% and other gases = 0.01%.

The oxides of sulphur and nitrogen present as pollutants in air react with water present in the atmosphere to form acids, which results in acid rain.

Carbon monoxide is not a greenhouse gas.

The increase in the average temperature of the earth’s atmosphere can cause global warming.

Dams are not the direct source of air pollution.

 Smog is formed in cold weather by combination of smoke and fog.

CFCs are responsible for depletion of ozone layer allowing UV rays to reach earth’s surface. UV rays are responsible for causing skin cancer.