MCQ on Air Pollution: Introduction and Explanation

Ans. b) CO

Explanation: Carbon Monoxide is the colorless, toxic, and odorless gas that is produced due to the incomplete burning of the wood. It is a poisonous gas and is produced along with carbon in the form of soot.

Ans. d) Both b and c

Explanation: The gases that trap the infrared radiations of the sun and prevent them from escaping into outer space are known as greenhouse gases. Methane, Nitrous Oxide, Carbon Dioxide, Chlorofluorocarbons, and Ozone along with water vapor are referred to as greenhouse gases. 

Ans. b) Primary Pollutants

Explanation: A primary pollutant is a pollutant that is directly emitted from a source. It includes ash, smoke, dust, sulphur dioxide, and nitric oxide.

Ans. a) Fog and Smoke

Explanation: Smog is formed from the combination of smoke that is formed of minute particles of ash, oil, carbon, etc, and fog in a suspended droplet form. It is a kind of intense air pollutant that lowers visibility levels. 

Ans. d) Both a and b

Explanation: The burning of fossil fuels leads to global warming and melting of the polar ice caps. The carbon dioxide and other gases trap heat and act as a blanket. Therefore, they lead to warming of the planet due to which polar ice caps melt.

Ans. a) Sulphur Dioxide

Explanation: When sulphur in the chimneys of industries reacts with oxygen in the atmosphere, sulphur dioxide is formed. This escapes into the atmosphere and reacts with the water molecules to form sulphuric acid and sulphurous acid. These acids lead to acid rain which is the main reason behind the changing color of the Taj Mahal as it causes the corrosion of the marble and turns it yellow.

Ans. c) Chlorofluorocarbons

Explanation: Chlorofluorocarbons are the fluoro and chloro substituted compounds of carbon are a major component of chemical smog. Photochemical smog is formed of both primary and secondary pollutants. 

The primary pollutants include volatile organic compounds and nitrogen oxides. They are introduced into the atmosphere by industrial processes and emissions by vehicles.

The secondary pollutants such as ozone are formed from the reaction of primary pollutants with ultraviolet light.

Ans. d) Aggravation of respiratory diseases

Explanation: Particulate Matter is a mixture of liquid droplets and solid particles that are found in the air. Particulate Matter can be released as a result of many human activities such as ash from industries, vehicle emissions, etc that can cause multiple health problems like respiratory diseases and heart attacks.

Ans. b) Aerosols

Explanation: A suspension of liquid droplets or fine solid particles in the air is known as aerosols. If the dispersion medium of the colloidal solution is air then the sol is referred to as an aerosol.

Ans. b) 78

Explanation: The air in the atmosphere is made up of 78 percent of Nitrogen and 21 percent oxygen. The other gases such as hydrogen, carbon dioxide, etc are also present in the air in small amounts. The composition of air is as follows:

• 78% of Nitrogen
• 20.9% of Oxygen
• 0.17% of Other gases
• 0.90% of Argon
• 0.03% of Carbon Dioxide

Ans. d) All of the above

Explanation: Plants play a very vital role to reduce the carbon dioxide in the atmosphere. They use CO₂ to make food and in turn, release oxygen. During the time of rain, water reacts with carbon dioxide in the atmosphere to form H₂CO₃ and therefore reduces the carbon dioxide in the atmosphere.

Ans. d) All of the above

Explanation: Air pollutants refer to those substances that are responsible for contaminating the air. The major sources of air pollutants are automobile exhausts, power plants, factories, etc.

Ans. c) Sulphur Dioxide

Explanation: Coal is a relatively inexpensive fuel source that produces useful energy. Various emissions are produced by the burning of coal such as bottom ash, fly ash, and sulphur dioxide. Sulphur Dioxide or SO2 plays a central role to produce acid rain and cause multiple respiratory problems.

Ans. c) The ultraviolet rays of the sun

Explanation: The ozone layer in the stratosphere region of the Earth's atmosphere acts as an invisible shield that protects human beings from harmful ultraviolet (UV) radiation from the sun. In the absence of an ozone layer shield, human beings will become more susceptible to skin cancer, cataracts and have an impaired immune system.

Ans. c) Acid Rain

Explanation: When pollutants like nitrogen dioxide and sulphur dioxide present in the air react with the water vapor in the atmosphere in order to form nitric acid and sulphuric acid. These acids then mix with the rain which makes it acidic leading to acid rain. This acid rain then corrodes the material of the buildings such as marble and leads to a phenomenon known as marble cancer.

Ans. b) It predicts the levels of ozone in an area

Explanation: Air Quality Index or AQI helps in determining the quality of the air in any area. This is based on the quantitative presence of multiple hazardous gases and does not determine the color of the air. The risk of diseases and public health risks increases as the Air Quality Index increases.