Pollution: UPSC Previous Year Questions (Environment and Ecology)

Explanation

At room temperature, benzene is a colorless or pale yellow liquid with a sweet odor and is highly flammable. It evaporates quickly into the air, and its vapor is denser than air, which can cause it to settle in low-lying areas. Benzene is a toxic air pollutant released from various sources and it can also contaminate water.

Option (a) is correct: Natural sources of benzene include volcanoes and forest fires. It is also present in gasoline, cigarette smoke, and crude oil, fuel evaporation, coal and oil combustion, and other activities. In various industries, benzene is used as a raw material to produce chemicals for making plastics, resins, nylon, and synthetic fibers. It is also found in the production of certain lubricants, rubbers, dyes, detergents, drugs, and pesticides. Although varnishes and paints may contain benzene, and the thermal breakdown of polyurethane can release benzene among other substances, these are not well-established as sources of benzene pollution.

Explanation

National Policy on Biofuels 2018 categorizes biofuels as "Basic Biofuels" viz. First Generation (1G) bioethanol & biodiesel and "Advanced Biofuels" - Second Generation (2G) ethanol, Municipal Solid Waste (MSW) to drop-in fuels, Third Generation (3G) biofuels, bio-CNG etc. to enable the extension of appropriate financial and fiscal incentives under each category. First-Generation Biofuels (also referred to as Basic biofuels) i.e. bioethanol and biodiesel, are produced from types of bio-mass that are often used for food, such as corn, soy, and sugarcane. These biofuels are made through fermentation or chemical processes that convert the oils, sugars, and starches in the bio-mass into liquid fuels. Second-Generation Biofuels (also referred to as Advanced bio-fuels) i.e, ethanol, municipal solid waste to drop-in fuels, are produced from non-food biomass, such as perennial grass and fast-growing trees. The processes to make them often involve converting fibrous non-edible material called "cellulose" into fuel. Third-generation biofuels are derived from algae and bacteria, which can produce large quantities of lipid oils or other biofuels like biomethanol or biohydrogen. Algae, in particular, grows quickly and has the potential to generate more biomass per unit of land compared to conventional crops.

Option (a) is correct: The Policy expands the scope of raw material for ethanol production by allowing the use of Sugarcane Juice, Sugar containing materials like Sugar Beet, Sweet Sorghum, Starch containing materials like Corn, Cassava, Damaged food grains like wheat, Broken rice, Rotten Potatoes.

Explanation

Social Cost of Carbon is best described as the measure of monetary value of long-term damage done by a tonne of CO₂ emissions in a given year. The social cost of carbon (SCC) is used to estimate in dollars all economic damage that would result from emitting one ton of carbon dioxide into the atmosphere. India’s country-level social cost of carbon emission was estimated to be the highest at $86 per tonne of CO₂. It means the Indian economy will lose $86 by emitting each additional tonne of CO₂. India is followed by the US ($48) and Saudi Arabia ($47).

Explanation

Statement 1 is correct: Coal ash contains contaminants like mercury, cadmium and arsenic. Without proper management, these contaminants can pollute waterways, groundwater, drinking water, and the air.

Statement 2 is correct: Burning of fossil fuels (which contain sulphur and nitrogenous matter) such as coal and oil in power stations and furnaces or petrol and diesel in motor engines produce sulphur dioxide and nitrogen oxides, which also leads to ‘acid rain’.

Statement 3 is correct: Indian Coal has comparatively higher ash content than imported coal due to the drift theory of the formation of coal deposits in India. Coal seams formed due to drift theory contain higher ash as compared to the in-situ theory of formation.