Agriculture & crops

Answer: (a) Only one

Only the first statement holds. India's arable land (about 155 million hectares) is second only to the USA's and larger than China's, but China irrigates a bigger share of its cropland and harvests far more per hectare.

• ✓ 1. FAO figures compiled by India's Agriculture Ministry put India's arable land at 155.37 million hectares in 2020, second in the world after the USA, which places it ahead of China.
• ✗ 2. About half of India's net sown area is irrigated and the rest depends on rainfall, while China irrigates a larger share of its smaller cropland.
• ✗ 3. China's yields are much higher: in 2020 its paddy yield was 7,043 kg per hectare against India's 4,138, and its wheat yield 5,742 kg against India's 3,440.

Remember · India: more arable land than China (second only to the USA). China: higher irrigation share of cropland and much higher yields per hectare.

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (b) Many marginal farmers in an area organize themselves into groups and synchronize and harmonize selected agricultural operations

UPSC's official key marks option (b) as correct; we could not confirm the definition of this concept from an official source, so we do not explain it here. A company that supplies loans, inputs and know-how to farmers for the crop it needs is contract farming (NCERT).

• ✓ (b) UPSC's official key marks this option as correct; we could not confirm the detail from an official source, so we do not explain it here.
• ✗ (d) A company supplying loans, inputs and know-how so that farmers grow the crop it needs is contract farming. NCERT describes it: the company identifies the crop, provides seeds and other inputs, and the know-how.
• ✗ (c) This option describes farmers handing their land to a corporate body for a fixed term against a payment; UPSC's official key does not mark it correct.

Remember · Company-led inputs-plus-buyback = contract farming (NCERT).

📘 Read it in NCERT: Class 12 Social Change and Development in India, Ch 4 (practise this chapter)

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink · Report an error

Answer: (c) All three

Nigerseed is one of the kharif crops for which the Centre announces a Minimum Support Price every year, and it is sown in the rainy season. UPSC's key counts all three statements as correct.

• ✓ 1. Nigerseed appears in the government's list of Minimum Support Prices for kharif crops; for 2022-23 the MSP was ₹7,287 per quintal.
• ✓ 2. Niger is sown in June–September as a kharif (and late-kharif) crop; official crop calendars list 'Niger (Kharif)' and 'Niger (Late Kharif)' seasons.
• ✓ 3. UPSC's official key counts this statement as correct; we could not confirm the detail from an official source, so we do not explain it here.

Remember · Nigerseed (Guizotia abyssinica): a kharif oilseed with an MSP notified every year.

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink · Report an error

Answer: (a) Devaraya I

Devaraya I of the Sangama dynasty built the great dam on the Tungabhadra and the long aqueduct that carried its water to Vijayanagara, according to the Portuguese chronicler Nuniz. NCERT confirms that the Hiriya canal drawing water from a dam across the river was built by Sangama kings.

• ✓ (a) Nuniz's account, as summarised by Robert Sewell, credits the ruler of this time, identified as Deva Raya I, with a huge dam on the Tungabhadra and an aqueduct fifteen miles long into the city.
• ✗ (b) Mallikarjuna was also a Sangama king, but Nuniz's account, as read by Sewell, names the ruler identified as Deva Raya I, not Mallikarjuna, as the builder.
• ✗ (c) Vira Vijaya is not the king named in Nuniz's account of the dam and aqueduct.
• ✗ (d) Virupaksha is likewise not named in that account; several of these kings were Sangamas, so the dynasty alone cannot pick the answer.

Remember · Devaraya I (Sangama): dam on the Tungabhadra and a long canal-aqueduct to Vijayanagara; the Hiriya canal is one of the surviving waterworks.

📘 Read it in NCERT: Class 12 Themes in Indian History, Part II, Ch 3 (practise this chapter)

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink · Report an error

Answer: (b) Only two

Statements 1 and 2 are counted as correct, and statement 3 is wrong. A biofilter is the waste-treatment unit of a recirculating fish farm: its bacteria turn toxic ammonia from fish waste and feed into less harmful nitrate, and it does not add phosphorus.

• ✓ 1. Waste treatment in a recirculating system includes removing waste solids, both faeces and uneaten feed, and the biofilter is part of that treatment train. Strictly, the mechanical filter removes solids and the biofilter handles dissolved nitrogen; UPSC's key counts this statement as correct.
• ✓ 2. Nitrifying bacteria in the biofilter convert ammonia into nitrite and finally into nitrate, which is far less toxic to fish than ammonia.
• ✗ 3. The biofilter removes toxic ammonia; it does not add phosphorus. Phosphate is an inert dissolved compound that simply passes through the filtration stage.

Remember · In a recirculating aquaculture system, the biofilter's nitrifying bacteria convert toxic ammonia to nitrite and then to less toxic nitrate. It adds no phosphorus.

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error