CHEMISTRY [2 Mark Question Answer]

The deterioration of air quality around us is called air pollution. Air pollution occurs because of the presence of gaseous pollutants such as oxides of sulphur, hydrocarbons, smoke, oxides of carbon, oxides of nitrogen, dust and particulate pollutants such as mist, spray, and fumes.

Methods to protect the ozone layer:

1. Using alternative products such as HCFCs (hydrochlorofluorocarbons)
2. Montreal Protocol, an international treaty, helps prevent ozone depletion.

Method of preventing acid rain:

1. By using coal or oil – that has low sulphur content. This reduces the emission of oxides of sulphur and nitrogen responsible for acid rain.
2. By using scrubbers a device that absorbs gaseous pollutants.

Effects of ozone depletion:

1. UV rays of the Sun reach Earth and cause sunburn, premature ageing of the skin and skin cancer.
2. The UV radiation can also damage several parts of the eyes, including the lens, cornea, retina, and conjunctiva.

Global warming is the increase in temperature of Earth due to the enhanced concentration of greenhouse gases (CFCs) in the atmosphere.
Two ways to reduce global warming:
Plant more trees to increase green cover
Minimize the use of automobiles.

Oxides of sulphur emission can be reduced,

• By using coal or oil which has low sulphur content.
• By using a scrubber, a device which absorbs gaseous pollutants.

A greenhouse collects light and converts it to heat. It also stores thermal energy and helps moderate temperature and produces a controlled environment for plants to grow and thrive. It even offers protection from wind, rain, snow and other weather elements and protects fruits from invading pests and animals.

Sources of water vapour:
Burning of hydrocarbons
Evaporation and transpiration
Effects of water vapour:
Greenhouse effect and global warming.

Methane
Sources of methane:
Anaerobic decomposition of organic matter in the soil, water and sediments
Incomplete combustion of fossil fuels
Effects of methane:
Greenhouse effect and global warming.

Carbon dioxide:
Sources of carbon dioxide:
Burning of fossil fuels such as coal, natural gas, and petroleum
Industrial processes such as the manufacture of lime and those in fermentation units
Biological decay of plants
Respiration by animals, human beings and plants
Effects of carbon dioxide:
Greenhouse effect and global warming.

Carbon dioxide reacts with water to form weak carbonic acid which is slightly acidic having a pH of about 5.6.
Hence, the pH of rainwater usually ranges between 5.6 and 3.5; at times, it can be as low as 2.

Smog is a dark, thick, dust and soot-laden fog pollutant which is a combination of oxides of nitrogen and sulphur and of partially oxidised hydrocarbons and their derivatives produced by industries and automobiles.
Smog is noxious and irritating. It reduces visibility, induces respiratory troubles and can cause death by suffocation.