UPSC Prelims: GS Paper II (CSAT) Exam Survival Guide

Pattern (verify each year): Objective, 200 marks, 2 hours, ~80 questions, qualifying at 33% (66 marks); negative marking (1/3). Sections usually include Reading Comprehension, Reasoning/Logic, Basic Numeracy & DI. 

Must-do skills (80/20)

• RC (biggest lever): main idea, inference, tone; line-evidence; eliminate out-of-scope/extremes.
• Reasoning: arrangements, syllogism/conditional (contrapositive), direction/sequence, coding, clocks/calendars.
• Quant/DI: % / ratio / averages & mixtures, TSD/work, simple algebra/ineq, Venn 2–3 sets, tables/line/bar/pie (TAUSL), basic geometry.

Top traps (and fixes)

• Over-investing in heavy quant → miss the 33% bar. Fix: RC + light quant/DI first.
• Reading RC options for “truth” not task. Fix: answer the stem; cite a line.
• Inequality flips / extraneous roots in algebra. Fix: write the sign step & check domain.
• Venn/DI base errors (rates vs counts; % vs pp). Fix: write base on the page before computing.

Time split (2 h, to clear 33% safely)

• RC first (45–55 min): aim 18–22 assured marks.
• Reasoning (30–35 min): clean sets (ordering/grid), skip rabbit holes.
• Quant/DI (25–30 min): arithmetic singles, light DI; leave 2-step algebra for last.
• Buffer (5 min): revisit 50–50s; no blind guesses (−1/3).

Last-48h checklist

• 2 CSAT sectionals (focus RC + light quant).
• Drill TAUSL on 6 charts; 20 arithmetic singles (percent/ratio/TSD/work).
• Logic kit: contrapositive, exactly-one (A⊕BA\oplus BA⊕B), at-most-one (pairwise ¬(A∧B)\neg(A\land B)¬(A∧B)); 4 mini-sets.
• Build a “no-calc” ring: %–fraction pairs, average-speed, mixture alligation, Venn formulas.

Quick frames

• RC map: topic • stance • structure (setup/evidence/counter/close).
• Logic: If A→BA\to BA→B then ¬B→¬A\neg B \to \neg A¬B→¬A; necessary vs sufficient.
• DI: convert units once, compute once; prefer ratios/bounds to heavy arithmetic.

Clear-the-bar plan (if time crunched)

1. 2 RCs you like → 1 DI set → 10–12 arithmetic singles.
2. Add one reasoning set you find clean.
3. Stop when your safe threshold (>70–75 marks raw) is crossed; protect accuracy.

Sources for pattern/marking (check each cycle)

• UPSC Prelims Notice 2025: two papers of 200 marks, CSAT qualifying at 33%, duration 2 hours each.
• UPSC FAQ (Examination): negative marking applies in objective papers. 

UPSC Previous Year Papers: typical counts ~100 Q (GS-I) and ~80 Q (GS-II/CSAT).