The Correct Answer is Lichen.

Concept:

The term “Bioindicators” refers to any organism, species, communities or biological processes, which help to qualitatively monitor the status of the environment in which they live by means of their function as well as their population.

• Any changes in the population status, behaviour, or physiology of such organisms can predict the occurrence of any environmental change or problem with the ecosystem.
• Bioindicators are living organisms such as plants, planktons, animals, and microbes, which are utilized to screen the health of the natural ecosystem in the environment.

Key Points

• Lichens are the best indicator of environmental pollution mainly SO₂. They are well known as sensitive indicators of air pollution, particularly for sulphur dioxide.
• SO₂ are emitted by the burning of fossil fuels like oil, coal and diesel or other materials that contain sulphur.

Additional Information

• A Pteridophyte is a vascular plant that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as 'cryptogams', meaning that their means of reproduction is hidden. Ferns, lycophytes and horsetails are all pteridophytes.
• Bryophytes are an informal group consisting of three divisions of non-vascular land plants: the liverworts, mosses and hornworts. The Bryophytes consist of about 20,000 plant species.
• Algae is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades.

The correct answer is Chlorine.

Key Points

• Chlorine (g) is not present in normal samples of air. It is a halogen.
• Chlorine is a chemical element with the symbol Cl and the atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them.
• Chlorine is a yellow-green gas at room temperature.
• Carbon dioxide is a product of cellular respiration, thus it is in the air.
• Traces of Neon are found in the air. It is a noble gas (odourless, colourless).
• Air is a mixture of various 'gases and water vapour. Its composition changes with altitude and pressure.
• Nitrogen, carbon dioxide and oxygen are part of the atmosphere but chlorine molecule does not form a part of the atmosphere.

Important Points

• The air in Earth’s atmosphere is made up of approximately 78 percent nitrogen and 21 percent oxygen.
• Air also has small amounts of lots of other gases, too, such as carbon dioxide, neon, and hydrogen. 

Key Points

• The electrostatic precipitator is one of the most widely used collection devices for particulates.
• An electrostatic precipitator (ESP) is a particulate collection device that removes particles from a flowing gaseous stream (such as air) using the force of an induced electrostatic charge.
• ESP can be operated at high temperatures and pressures, and its power requirement is low.
• An electrostatic precipitator is a type of filter (dry scrubber) that uses static electricity to remove soot and ash from exhaust fumes before they exit the smokestacks.

The efficiency of different types of air-filtering devices is as follows:

The correct answer is All I, II and III.

Key Points

• CNG, also known as compressed natural gas, is an eco-friendly alternative to gasoline.
• Made by compressing natural gas (methane) down to less than 1% of its volume.
• CNG fuel is safer than gasoline and diesel because it is non-toxic and does not contaminate groundwater.
• This natural gas is the same gas that you use daily to heat your home and water, cook on the stove and oven to dry your clothes in a dryer.
• The use of CNG fuel is becoming more popular with both commercial and non-commercial vehicles.
• This is considered to be a cleaner gas because it causes less pollution as compared to other fuels like petrol or diesel.
• It exhausts a lesser amount of nitrogen dioxide, carbon dioxide, and sulphur dioxide while burning as compared to other fuels.
• So all the options regarding CNG gas is correct.

The correct answer is Central Pollution Control Board.

• The Central Pollution Control Board (CPCB) of India is a statutory organization under the Ministry of Environment, Forest and Climate Change (Mo.E.F.C.C.). 
•  It was established in 1974 under the Water (Prevention and Control of Pollution) Act, 1974. 
• The CPCB is also entrusted with the powers and functions under the Air (Prevention and Control of Pollution) Act, 1981.
• The board has approximately 500 full-time employees.
• It Coordinates the activities of the State Pollution Control Boards by providing technical assistance and guidance and also resolves disputes among them.
• It is the apex organization in the country in the field of pollution control, as a technical wing of MoEFCC.

Additional Information

•  Central Pollution Control Board (CPCB) was formed on 22 September 1974.
• The chairperson of CPCB is Dr Prashant Gargava.
• Environmental Pollution Control Authority is a pollution controlling agency only for the National Capital Region (NCR).

Concept:

Air pollutants:

Pollutants are classified in different ways. According to origin pollutants are two types.

1). Primary pollutants:

• These are directly emitted from the sources in the atmosphere in a harmful form.
• They can be natural (volcanic eruptions or fires, for example) or of anthropogenic origin (carbon monoxide from vehicles).

2). Secondary Pollutants:

• These are derived from primary pollutants due to chemical or photochemical reactions in the atmosphere they become hazardous after reaction in the air. 
• The best known of the secondary pollutants is certain gases that are synthesized by photochemical reactions in the lower atmosphere.
• The primary emitted chemicals in these reactions are hydrocarbons and gaseous oxides of nitrogen such as nitric oxide and nitrogen dioxide. 
• Its origin lies in the interactions between the primary emissions in the atmosphere.

Examples of primary and secondary air pollutants:

The Correct Answer is Option 4 i.e Methane.

• National AQI is determined on the basis of concentration of 8 pollutants namely Particulate Matter (PM 2.5, PM 10), sulphur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), ozone (O₃), ammonia (NH₃) and lead (Pb).
• Ozone (O₃):
  • Ozone (O₃) is a highly reactive gas composed of three oxygen atoms.
  • It is both a natural and a man-made product that occurs in the Earth's upper atmosphere (the stratosphere) and lower atmosphere (the troposphere).
  • Stratospheric ozone is formed naturally through the interaction of solar ultraviolet (UV) radiation with molecular oxygen (O₂).
• Nitrogen Dioxide (NO₂):
  • It is one of a group of gases called nitrogen oxides (NOx).
  • NO2 primarily gets in the air from the burning of fuel. 
  • NO2 forms from emissions from cars, trucks and buses, power plants, and off-road equipment.
  • Some nitrogen dioxide is formed naturally by plants, soil and water.
• Sulphur dioxide (SO₂):
  • It is a colorless gas with suffocating odour.
  • Burning of fossil fuels by power plants and other industrial facilities are the largest source of SO₂ in the atmosphere.
  • It is also released as a natural byproduct of volcanic activity.

One carbon credit is accepted as equivalent to 1000 kg of carbon dioxide.

Carbon credit:

• It is the difference between the carbon emissions allowed and actually emitted carbon.

Key Points

• A carbon credit is a permit that allows the company that holds it to emit a certain amount of carbon dioxide or other greenhouse gases.
• One credit permits the emission of a mass equal to one ton of carbon dioxide.
• One credit permits the emission of a mass equal to one ton of carbon dioxide. 

Additional Information

• The United Nations' Intergovernmental Panel on Climate Change (IPCC) developed a carbon credit proposal to reduce worldwide carbon emissions in a 1997 agreement known as the Kyoto Protocol.
• The agreement set binding emission reduction targets for the countries that signed it.
• Another agreement, known as the Marrakesh Accords, spelt out the rules for how the system would work.

Note:

A proposal for Carbon credit was presented by IPCC and ratification of the International carbon credit system is in agreement with the Kyoto Protocol.

Key Points

The preventive measure for water and air pollution is

• Public consciousness: Peoples should be aware of their social responsibilities against pollution. They should know about the adverse effects caused due to pollution.
• Industrial cooperation: Industrial wastes and ashes are one of the major causes of water and air pollution.
• Taken by the Legislative Council: CPCB is also entrusted with the powers and functions under the Air (Prevention and Control of Pollution) Act, 1981 and the Water (Prevention and Control of Pollution) Act established in 1974.

Important Points

Water (Prevention and Control of Pollution) Act – This law was meant for checking and preventing water pollution, which had become prominent at the time of enactment of this law. Due to this, a central board called the Central Board for the prevention and Control of Water Pollution was formed.

Water (Prevention and Control of Pollution) Cess Act – This act promoted recycling and reuse of the wastewaters. It proved effective in reducing the quantities of industrial wastes.

Air (Prevention and Control of Pollution) Act – This act was to control and monitor air pollution in the environment. The Water Pollution Control Boards were given the additional charges of looking after air pollution control also.

The Environment (Protection) Act – This act subsequently promulgated by the Parliament after the occurrence of the Bhopal Gas Tragedy. This act empowers the Central Government for taking any measures, for improving and protecting the environment.  

Key Points

Air Quality Index (AQI) value between 401-500 is considered hazardous for public health.

Following 5 major air pollutants are calculated by the Environmental Protection Agency (EPA) for which national air quality standards have been established to safeguard public health.

1. Ground-level ozone
2. Particle pollution/particulate matter (PM2.5/PM 10)
3. Carbon Monoxide
4. Sulphur dioxide
5. Nitrogen dioxide

Air Quality Index (AQI) and its impacts on public health: