UPSC Prelims 2022 Q21-30 Solved: The Sherlocking Method

This is part 3 of the Sherlocking Prelims 2022 analysis, covering questions 21 to 30 of Set A. The whole point is to show that the so-called "toughest Prelims in 10-15 years" was still crackable with just two ingredients: basic sources and common sense. Across these ten questions you will see how an overview beats in-depth knowledge, how to reason through facts you do not remember, and exactly when to leave a question alone.

Key takeaways

• The winning formula is repeated like a mantra: basic sources plus common sense. An overview is rewarded more than deep, fancy knowledge.
• "Sherlocking" simply means being observant - once you have read enough, the answer to an MCQ is already in front of you; your job is to spot it.
• Occam's razor works in the exam hall: when several explanations are possible, back the simplest one.
• A later question can hand you the answer to an earlier one - reading attentively pays off.
• For questions you never studied, look for keyword-based logical correlations rather than wild guesses.
• Two similar-sounding options usually hide the right answer - a by-product of how examiners construct questions.
• Know when to leave: with ~94 attempts, Neil Sir still had the leeway to skip 15 questions safely.

The Sherlocking philosophy: basic sources plus common sense

The series rests on one principle. You do not need encyclopaedic recall; you need an overview of standard sources plus the common sense to apply it under pressure. That common sense does not appear overnight - it is built through repeated analysis of previous year questions until the heuristics become second nature.

Neil Sir leans on Occam's razor: when a question offers several possible explanations, the simplest one is usually correct. In Q21 (the most important anthropogenic source of both methane and nitrous oxide), the moment "methane" appears, a serious aspirant connects it to paddy fields. Without knowing rice's contribution to nitrous oxide or cotton's to methane, the simplest connection points to rice - and that hunch is right.

A neat bonus: Q22 actually gives away Q21. The System of Rice Intensification question states that the practice results in "reduced methane production," confirming that rice cultivation produces methane. Reading attentively can win you a second mark.

Backing your hunch on factual MCQs

Several questions can be cracked by reasoning about why a fact would be true, not by recalling it.

Q22 - System of Rice Intensification

The question lists three outcomes of SRI: reduced seed requirement, reduced methane production, and reduced electricity consumption. Logic says a system humans deliberately developed would only be adopted if it brings benefits - and all three statements carry positive connotations. So all are correct, and the answer is the "all of the above" style option. Neil Sir had not read SRI in depth, only reasoned it out.

Q28 - Monazite

For the statements on monazite, the key is spotting how one statement flows from another. Monazite contains thorium (a nuclear fuel), so it makes sense that only government bodies process or export it - statement four flows logically from statement two. That leaves the suspicious statement: monazite occurring "in the entire Indian coastal sands" is an extreme, absolute claim. If it is absent from even one coastal stretch, the statement fails. Eliminate the extreme statement, and you arrive at the answer.

Q29 - Longest day of the year

A genuinely basic question - NCERT class 6 to 8 level. In the northern hemisphere the longest day occurs at the summer solstice, on 21 June, which falls in the second half of the month. No fancy source required.

Solving questions you never studied

This is where Sherlocking shines - extracting answers from questions where you have zero direct knowledge.

Q23 - The dried-up lake in West Africa

Neil Sir did not know the lake. So he took the only usable keyword: West Africa. West Africa was largely colonised by the French, so the lake's name is more likely to sound French than English. Lake Victoria is an English name (and sits in East Africa, a source of the Nile), so it goes. Among the rest, the French-sounding option stood out - a knack he credits partly to following football and hearing players' names from across the continent.

Q26 - The term "Levant"

He offers three independent routes. First, two options both mention "Mediterranean," and the answer is more likely to sit between two similar-sounding options. Second, between a specific eastern Mediterranean stretch and the entire coastal area, a specialised term usually maps to the smaller, specific region. Third, tangential current affairs: ISIS was also called ISIL, where the "L" stands for Levant - the eastern Mediterranean region.

Q27 - Afghanistan's neighbours

You need not memorise every neighbour. With a rough mental map - Caspian Sea, Persian Gulf, Horn of Africa - Neil Sir was confident only that Azerbaijan does not border Afghanistan. Eliminating that single wrong option delivers the answer. An overview, not depth, did the job. The same elimination logic cracked Q25 (Himalayan peaks) and Q30 (wetlands), where knowing that obviously wrong pairs - a peak placed in the wrong state, or a famous Ramsar site like Hokera (J&K), Renuka (Himachal), Rudrasagar (Tripura) or Sasthamkotta (Kerala) wrongly matched - lets you eliminate without knowing the trickiest pair.

Read the options like the examiner

A recurring tool here is the examiner's constraint. UPSC examiners usually build questions from scratch, so they start with the correct answer and then craft three plausible distractors - close enough to confuse, but not impossibly hard. The result: similar-sounding options often bracket the right answer. Spotting this pattern let Neil Sir confidently eliminate the odd-ones-out in Q26 before reasoning between the two survivors.

When to leave a question

Q24 - the river that created Gandikota, the "Grand Canyon of South India" - had no logical hook. Neil Sir only got it (the Penna) because he had visited Gandikota in person. He calls this a "Slumdog Millionaire" question: answerable purely by lived experience, and everyone gets one or two. The lesson is the opposite of guessing wildly - if there is no keyword to reason from, leave it. With around 94 attempts and a comfortable buffer, skipping 15 questions costs nothing.

How many to attempt and the cutoff

Neil Sir's read: an attempt of 80-85 is excellent for civil services, while IFoS aspirants should push to 92-95 since that cutoff is higher. In his estimate the 2022 cutoff would hover around 85 and not exceed 90. Across just the first 30 questions, basic sources plus common sense already secure enough correct answers to put you within touching distance of clearing.

Who should watch this

This is for serious Prelims aspirants - especially those a year or more into the cycle - who keep losing nerve on "unknown" questions. If you have done your NCERTs, Laxmikanth and basic geography but freeze in the hall, this analysis rewires how you attack the paper.

The biggest gains come from doing this yourself, repeatedly, until the heuristics are internalised. Pair this analysis with structured Prelims test series practice, and keep working through the rest of the guides on the blog to build the common sense that no compilation can hand you.