Pollution & waste

Answer: (a) environmentally responsible practices in electronics recycling industry

R2 stands for 'Responsible Recycling', a certification standard for electronics recyclers. Recyclers audited against it show that they handle used electronics and e-waste safely for the environment, workers and data security.

• ✓ (a) The R2 (Responsible Recycling) Standard is one of two accredited certification standards the US Environmental Protection Agency recognises for electronics recyclers.
• ✗ (b) Ramsar sites are managed under the Ramsar Convention's own guidance, such as the Montreux Record; R2 has nothing to do with wetlands.
• ✗ (d) Environmental Impact Assessment is a separate regulatory process for projects, not the R2 recycling code.

Remember · R2 = Responsible Recycling, a voluntary certification for electronics (e-waste) recyclers; its main counterpart is the e-Stewards standard.

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (b) 2 and 3 only

Most copper comes from sulphide ores, so smelting them drives off sulphur dioxide, a major air pollutant. The glassy waste left behind, copper slag, still carries heavy metals that can contaminate soil and water if stored carelessly. Releasing lethal amounts of carbon monoxide is not the recognised hazard of these plants.

• ✗ 1. The air-pollution concern linked to smelting ores that contain sulphur is sulphur dioxide, not lethal quantities of carbon monoxide; UPSC's key treats statement 1 as wrong.
• ✓ 2. Copper slag (Ferro sand) contains arsenic, cadmium, chromium, cobalt, nickel, lead and zinc, and the CPCB guideline asks smelters to store slag on an impermeable base with a garland drain to prevent soil and groundwater contamination.
• ✓ 3. Roasting and smelting sulphide ores releases sulphur dioxide; the WHO lists the smelting of sulphur-bearing ores as a main source of SO2.

Remember · Copper smelters: sulphur dioxide (from sulphide ores) in the air, and heavy-metal leaching from slag heaps.

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink · Report an error

Answer: (d) 1, 2 and 3

Furnace oil is a heavy residual fuel left after the lighter fractions are distilled from crude oil in a refinery. Industries burn it in boilers, furnaces and captive power plants, and because it is rich in sulphur, burning it releases sulphur dioxide. All three statements hold.

• ✓ 1. It is the heavy residue that remains after refineries distil off the lighter products, which is why it is also called residual fuel oil.
• ✓ 2. Heavy fuel oil is used to produce electric power and for many industrial heating purposes, including captive generation.
• ✓ 3. Burning oil that contains sulphur emits sulphur dioxide, and furnace oil is among the higher-sulphur fuels, so its use adds SO2 to the air.

Remember · Furnace oil = heavy residual refinery product; burnt in industrial boilers and power units; high sulphur, so a source of SO2.

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (b) 1, 2 and 4 only

Pollution-derived magnetite nanoparticles form when iron-bearing material is burnt or heated by friction, so they come from vehicle engine exhaust, brake wear and combustion at power stations. A 2016 study found such particles in human brain tissue and linked them to oxidative damage of the kind seen in Alzheimer's disease. Microwave ovens and telephone lines are not among the sources it names.

• ✓ 1. Frictional heating of brake pads produces high-temperature magnetite nanoparticles at the roadside.
• ✓ 2. Magnetite nanoparticles have been captured from the exhaust plume of diesel engines; combustion is the main source.
• ✗ 3. The study names open fires and poorly sealed cooking or heating stoves as indoor sources of magnetite nanoparticles; microwave ovens are not among them.
• ✓ 4. The study shows spherical, fused magnetite particles collected at a power station, an example of industrial combustion.
• ✗ 5. Telephone lines are not among the sources the study names; they carry electrical signals, not iron-oxide particles from combustion or friction.

Remember · Airborne magnetite nanoparticles come from combustion and friction: vehicle exhaust, brake wear, power plants, open fires. They have been found in human brain tissue.

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink · Report an error

Answer: (b) Polycarbonate

BPA is the building-block chemical of polycarbonate, the hard, clear plastic used in reusable bottles and food containers. It is also used in epoxy resins, such as the lining of food cans. The official agencies name only these two plastics as its main uses, so the other options fail.

• ✓ (b) Polycarbonate is made by joining BPA units, so BPA is a structural part of it. Small amounts can leach into food or drink, which is why BPA is a health concern (it can act on the hormone system).
• ✗ (a) Low-density polyethylene (carry bags and films) is not among the plastics that US and EU agencies name as made with BPA; they name polycarbonate and epoxy resins.
• ✗ (c) PET, the plastic of soft-drink and water bottles, is not among the plastics that US and EU agencies name as made with BPA; polycarbonate is the BPA-based bottle plastic.
• ✗ (d) Polyvinyl chloride is not among the plastics that US and EU agencies name as made with BPA; they name polycarbonate and epoxy resins.

Remember · BPA goes into polycarbonate plastics and epoxy resins (can linings). It is a suspected hormone disruptor.

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink · Report an error

Answer: (d) Toiletries

Triclosan is an antibacterial chemical added to personal-care products such as some soaps, skin cleansers, deodorants and toothpastes, which are toiletries. It is a suspected endocrine (hormone-system) disruptor, so long exposure to high levels is a worry.

• ✓ (d) The US FDA says triclosan is added to some antibacterial soaps and body washes, toothpastes and cosmetics, all toiletries. Some short-term animal studies link high doses to lower levels of some thyroid hormones, which is why long exposure is a concern.
• ✗ (a) Food preservatives keep food from spoiling; triclosan is not a permitted food preservative. It is an antibacterial for personal-care products.
• ✗ (b) Fruit-ripening substances are chemicals that release ethylene, the ripening hormone of plants. Triclosan is not a ripening agent.
• ✗ (c) Triclosan is mainly an antibacterial added to personal-care products. The usual worry about reused plastic containers is a different one: chemicals such as BPA leaching out of the plastic.

Remember · Triclosan is an antibacterial agent in toiletries (soaps, toothpaste, deodorants) and a suspected endocrine disruptor.

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink · Report an error