Air Pollution Test - 2

Oxygen is not consumed during volcanic eruptions.
It is used by the living organisms for respiration.
It is a basic requirement for all burning processes.

Some amount of atmospheric oxygen also dissolves in water bodies and hence, it is available for the aquatic plants and animals.

The complete statements are:
I. Air supports combustion because of the presence of oxygen gas in it.
II. The most abundant gas in the air is nitrogen.
III. Carbon dioxide and methane keep the Earth warm even after sunset because they absorb some of the heat radiated by the Earth.
IV. Argon is the most abundant noble gas in the air.

Troposphere is the lowest part of the atmosphere which is where most of our weather phenomena like clouds, rain, snow occur. In this part of the atmosphere, the temperature gets colder as the distance above the Earth increases, by about 6.5°C per kilometre. The actual change of temperature with height varies from day to day, depending on the weather.

Ozone is abundant in the stratosphere. The atmosphere gets heated upwards in this layer because the UV rays react with oxygen molecules to continuously form ozone with heat as the byproduct.

The ozone being an unstable molecule absorbs the UV rays and disintegrate to form oxygen again, and releasing heat energy in the process.

The fossil fuels like petrol, diesel, kerosene that are used as automobile fuels add carbon dioxide, sulphur dioxide, nitrogen oxides, etc. to the atmosphere which have adverse effects on the environment.

Hydrocarbons are released due to incomplete combustion in the engines. This not only leads to wastage of fuel but also causes smog.

NOTE: Although carbon dioxide is essential for photosynthesis, it is a pollutant when present in excess as it contributes to global warming.

Use of CNG helps to control pollution as it is a cleaner fuel in comparison to petrol and diesel and produces lesser amount of pollutants.

Petrol and diesel are basically mixtures of hydrocarbons (compounds of carbon and hydrogen).
On burning these fuels with an adequate amount of oxygen, the combustion products are formed in the form of carbon dioxide and water, along with the production of a sufficient amount of energy.

However, in an inadequate supply of oxygen, carbon monoxide is formed which is a poisonous gas as it combines with the haemoglobin in the blood, thereby reducing its availability as an oxygen carrier.

Therefore, both statements I and II are correct and statement II is the correct reason for I.

All the given statements are correct as photochemical smog is summer smog produced when ultraviolet light from the sun reacts with nitrogen oxides in the atmosphere.

NO₂ goes through a complex series of reactions with hydrocarbons to produce the components of photochemical smog - a mixture of ozone, nitric acid, aldehydes, peroxyacyl nitrates (PANs) and other secondary pollutants which create a haze that reduces the visibility and also leads to respiratory problems.