JEE Questions for Chemistry Environmental Chemistry Quiz 1 - MCQExams.com

The man-made component of the greenhouse effect is caused by man’s activities that emit greenhouse gases to the atmosphere. The most important of these is the burning of fossil fuels. Fossil fuels contain carbon, and when they are burnt this carbon combines with oxygen in the atmosphere to form carbon dioxide.

 The primary cause of ozone depletion is the presence of chlorine-containing source gases (primarily CFCs and related halocarbons) and oxides of nitrogen. In the presence of UV light, these gases dissociate, which then go on to catalyze ozone destruction. Hence methane is not responsible for the depletion of ozone layer.

The gases in the atmosphere that absorb radiation are known as "greenhouse gases" (sometimes abbreviated as GHG) because they are largely responsible for the greenhouse effect. The greenhouse effect, in turn, is one of the leading causes of global warming. The most significant greenhouse gases are water vapor (H₂O), carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) and ozone (O₃). While oxygen (O₂) is the second most abundant gas in our atmosphere, O₂ does not absorb thermal infrared radiation to cause green house effect.

Among the given options , Nitrogen (N₂) is not an airpollutant. Because Nitrogen makes up most of our atmosphere 78% of our atmosphere is N₂

1. Polar stratospheric clouds (PSCs) are the medium on which reservoir chlorine compounds are converted into ozone –destroying chlorine radicals , they are essentially two types of  PSC known as type 1 and type 2.
2. Polychlorinated  biphenyl (PCBs) is a group of organic compounds used in the manufacture of plastics, as lubricants, in transformers, adhesives and so forth.They are highly toxic to aquatic life and persist in the environment for long periods of time. They can accumulate in food chains and may produce harmful side-effects at high concentrations
3. Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed (i.e demaned ) by aerobic biological organisms to break  down organic material present in a given water sample at certain temperature over a specific time period .

Chemical oxygen demand (COD) is defined as a  measure of the oxygen equivalent of the organic matter content of a sample that is susceptible to oxidation by a strong chemical oxidant . Therefore, BOD is a measurement of water pollution.

The Bhopal disaster or Bhopal gas tragedy was a disaster that resulted from an accident. It happened at a union carbide subsidary pesticide plant in the city of Bhopal, India on 3,December 1984, the plant released 42 tonnes of toxic methyl isocyanate (MIC) gas, exposing more than 5,00,000  people to toxic gas.

The main cause of ozone depletion is the widespread use of chlorofluoro carbons (CFCs). Hence they eat away the ozone in the atomosphere.

DDT is a non-biodegradable pollutant. It cannot be broken down into simple and harmless substance.

Ozone is so effective at absorbing the sun's UV radiation that this small amount is plenty enough to protect us on Earth and also permits the infrared radiations to pass through it.

The ozone layer or ozone shield refers to a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet (UV) radiation. It contains high concentrations of ozone (O₃) relative to other parts of the atmosphere, although still very small relative to other gases in the stratosphere. 

The smog is essentiallly caused by presence of oxides of sulphur and nitrogen, i.e NO, NO₂ , SO₃ and SO₂ are mainly responsible for smog.

Freons are chlorofluorocarbons and are responsible for depletion of ozone layer. 

The severe depletion of the anttartic ozone layer known as the ozone hole occurs because of the special atmospheric and chemical conditions that exist there and no where else o  the globe. The very low winter temperatures in the Antarctic stratosphere cause polar stratospheric clouds (PSCs) to form. These clouds contain

Chlorine nitrate (ClONO₂)

SO₂ has no contribution in photochemical smog.