Minerals, energy & industry

Answer: (a) Crude oil

West Texas Intermediate (WTI) is a grade of crude oil produced in Texas and southern Oklahoma. It is a reference ("marker") crude whose price is used to price many other crude streams, which is why it appears so often in oil-price news.

• ✓ (a) WTI is a crude stream from Texas and southern Oklahoma, traded in the US spot market at Cushing, Oklahoma, and used as a pricing benchmark for other crude oils.
• ✗ (b) Bullion means precious metal, mainly gold or silver, held in bulk; WTI is a grade of oil, not a metal.
• ✗ (d) Uranium is a nuclear fuel mineral; WTI has nothing to do with it.

Remember · WTI is a US crude oil benchmark, traded in the spot market at Cushing, Oklahoma.

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Answer: (d) 1, 2 and 3

Steel slag, the solid waste left when steel is made, is usable in all three ways: as stone-like aggregate in road layers, as a soil conditioner in farming, and as an ingredient in cement.

• ✓ 1. Processed steel slag replaces natural stone aggregate in roads; CSIR-CRRI has framed guidelines for using it in various road works, and a six-lane highway near Surat was built with it.
• ✓ 2. The Ministry of Steel lists agriculture as a use, where the slag stands in for soil nutrients and fertilisers, and its website mentions soil conditioning.
• ✓ 3. The Ministry of Steel names 'green cement' among the uses of steel slag; note that blast-furnace (iron) slag is the type mostly used in cement making today.

Remember · Steel slag is a waste-to-wealth material: road aggregate, soil conditioner, cement ingredient and rail ballast.

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Answer: (d) 1, 2 and 3

All three statements are correct: coal ash carries toxic trace metals such as arsenic, lead and mercury, coal-burning power plants emit sulphur dioxide and nitrogen oxides, and Indian coal is high in ash.

• ✓ 1. Coal and its fly ash hold toxic trace elements; the US Geological Survey names arsenic, selenium, lead and mercury among those tested in fly ash.
• ✓ 2. CPCB's standards for coal-based thermal power plants set limits for sulphur dioxide and oxides of nitrogen in the flue gas, because burning coal releases both.
• ✓ 3. The Ministry of Coal states that coal produced in India generally has 25 to 45 per cent ash, against 10 to 20 per cent for imported coal, which is why washing of coal is promoted.

Remember · Coal power means SO2 and NOx in the air and ash laden with arsenic, lead and mercury on the ground; Indian coal is high in ash.

📘 Read it in NCERT: Class 11 Indian Economic Development, Ch 7 (practise this chapter)

Question and answer: UPSC's official GS Paper I (2020, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (a) 1, 2, 5 and 6 only

The National Policy on Biofuels (2018) allows ethanol to be made from cassava, sugar beet, rotten potatoes and damaged food grains such as wheat that are unfit for human consumption. Groundnut and horse gram are edible crops, and the policy's biodiesel route is limited to non-edible oils.

• ✓ 1. The policy names cassava among the starch-containing materials for bioethanol.
• ✓ 2. It lists damaged food grains like wheat and broken rice that are unfit for human consumption as ethanol feedstock.
• ✗ 3. Groundnut is an edible oilseed; the policy's biodiesel feedstock is non-edible vegetable oil, acid oil, used cooking oil or animal fat.
• ✗ 4. Horse gram is a food pulse and is not named as a biofuel raw material.
• ✓ 5. Rotten potatoes are listed among the starch-containing materials.
• ✓ 6. Sugar beet is named among the sugar-containing materials, along with sugar cane and sweet sorghum.

Remember · Biofuel policy feedstock: sugar (cane, beet, sweet sorghum), starch (corn, cassava, rotten potato), unfit food grains for ethanol; non-edible oils and used cooking oil for biodiesel.

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Answer: (d) Neither 1 nor 2

Neither statement is correct. A solar panel only supplies electricity, so it can drive any suitable motor-pump: the Ministry of New and Renewable Energy's own specification lists both surface and submersible pump sets for solar water pumping, and piston (positive-displacement) pumps can be powered too.

• ✗ 1. MNRE's specification says solar photovoltaic water pumping systems may use a surface mono-set or a submersible motor-pump set.
• ✗ 2. MNRE's PM-KUSUM material names two types of solar water pump, centrifugal and positive displacement, and MNRE has a separate specification for solar pumping systems with positive-displacement pumps. Solar power is not limited to centrifugal pumps.

Remember · Solar pumps are just electric pumps fed by panels: surface or submersible, AC or DC, centrifugal or positive-displacement can all be used.

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Answer: (d) 2, 3 and 4 only

Chromite, kyanite and sillimanite are major minerals, which the Central Government regulates and the Indian Bureau of Mines tracks in its national mineral inventory. Bentonite is not a major mineral; it is treated as a minor mineral, which States regulate.

• ✗ 1. The Indian Bureau of Mines states that bentonite has been declared a minor mineral under Section 3(e) of the MMDR Act, 1957, so its production is reported to the States, not to IBM, and it is not counted as a major mineral.
• ✓ 2. Chromite, the ore of chromium, is a major (metallic) mineral and is listed in the national mineral inventory.
• ✓ 3. Kyanite is a major mineral and is listed in the national mineral inventory.
• ✓ 4. Sillimanite is a major mineral and is listed in the national mineral inventory.

Remember · Chromite, kyanite and sillimanite are major minerals tracked in the national mineral inventory; bentonite, a clay, is not a major mineral.

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Answer: (b) 2 and 3 only

Statements 2 and 3 are correct; statement 1 is not. Urea, India's main fertiliser, is sold at a maximum retail price fixed by the Government, so the retail price of chemical fertilizers is not wholly market-driven.

• ✗ 1. Urea is sold to farmers at a statutorily notified Maximum Retail Price, whatever its cost of production. Only phosphatic and potassic fertilizers (under the Nutrient Based Subsidy scheme) have prices set by the companies, so 'not administered' is not true for fertilizers in general.
• ✓ 2. Ammonia is made from hydrogen and nitrogen, and natural gas is the main source of the hydrogen (steam reforming). Ammonia is then reacted to make urea.
• ✓ 3. India's elemental sulphur output is largely recovered as a by-product at petroleum refineries. It is turned into sulphuric acid, which is used to make phosphoric acid from rock phosphate.

Remember · Urea has a Government-fixed MRP; P&K prices are company-set under the NBS scheme. Ammonia comes from natural gas; by-product sulphur comes from refineries.

Question and answer: UPSC's official GS Paper I (2020, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error