ISC Class 12 Last Minute Revision
Subject-specific 24-hour guides for ISC Class 12. Focus topics, timing strategy, and the mistakes that cost marks — for each subject.
Physics
Focus Topics
- →Gauss's Law applications and electric field derivations
- →Biot-Savart Law vs Ampere's Law — when to use which
- →Faraday's and Lenz's Law — numerical problems
- →Snell's Law, total internal reflection, critical angle
- →Photoelectric effect — threshold frequency, stopping potential
- →Nuclear reactions — Q value, binding energy per nucleon
Time Strategy
Section A (MCQs) first — 20 mins. Section B (short answers) — 50 mins. Section C (long answers) — 90 mins. Keep 20 mins for checking.
Common Mistakes
- ✗Not stating the law before applying it in derivation questions
- ✗Skipping units in numerical answers — ISC deducts marks for this
- ✗Confusing sign conventions for mirrors and lenses
Chemistry
Focus Topics
- →Electrochemistry — Nernst equation, cell potential calculations
- →Chemical kinetics — integrated rate laws, half-life formulas
- →d- and f-Block Elements — KMnO₄ and K₂Cr₂O₇ reactions, oxidation states
- →Coordination compounds — IUPAC naming, isomerism types
- →Aldol condensation, Cannizzaro reaction, nucleophilic addition
- →Amino acids — zwitterion form, isoelectric point
Time Strategy
Complete all MCQs first (15 min). Short answer questions in order — 45 min. Long answers: choose wisely — 70 min. Revise calculations — 20 min.
Common Mistakes
- ✗Writing IUPAC names without checking oxidation state of metal
- ✗Forgetting conditions (reagent, temperature) in reaction mechanisms
- ✗Not balancing half-equations in electrochemistry
Mathematics
Focus Topics
- →Integration by parts — LIATE rule and definite integrals
- →Determinants — properties and applications to solve systems
- →Application of derivatives — maxima/minima, rate of change
- →3D Geometry — direction cosines, angle between lines/planes
- →Probability — Bayes' theorem, binomial distribution
- →Differential equations — variable separable and linear forms
Time Strategy
Section A mandatory (65M) — attempt all, 100 mins. Section B OR Section C (15M) — choose ONE, 50 mins. Do not attempt both B and C.
Common Mistakes
- ✗Attempting both Section B and C — only one is allowed
- ✗Not writing the constant of integration in indefinite integrals
- ✗Forgetting to check boundary conditions in differential equations
Biology
Focus Topics
- →Human reproduction — stages of gametogenesis, placenta functions
- →Mendelian genetics — dihybrid cross, codominance, linkage
- →DNA replication — leading and lagging strand differences
- →Immune system — types of immunity, vaccination mechanism
- →Biotechnology — PCR steps, gel electrophoresis, rDNA technology
- →Ecosystem — energy flow, nutrient cycling, ecological pyramids
Time Strategy
Part I (30M) in 45 mins — answer all. Part II choose 3 from 6 (15M each) — 90 mins. Diagrams in Part II carry 4–5 marks; draw them carefully.
Common Mistakes
- ✗Drawing diagrams without proper labels — every arrow and structure must be named
- ✗Confusing mitosis and meiosis stages in questions about cell division
- ✗Missing the word 'biodegradable' vs 'non-biodegradable' in pollution answers
English
Focus Topics
- →Paper 1 — Comprehension: answer in your own words, no copying
- →Letter writing — format must be perfect: address, date, salutation, body, closing
- →Report writing — use third person, past tense, formal register
- →Grammar — transformation of sentences, active/passive voice
- →Paper 2 — Literature: quote accurately, analyse literary devices
- →Poetry questions — identify the poem, explain the mood and theme
Time Strategy
Paper 1 (3 hrs): Q1 Comprehension 50 mins · Q2 Writing 60 mins · Q3 Grammar 40 mins · Q4 Vocabulary 30 mins. Paper 2 (3 hrs): allocate 50 mins per question.
Common Mistakes
- ✗Copying sentences from the passage in comprehension — paraphrase instead
- ✗Writing informal English in formal letter/report formats
- ✗Not quoting the text when analysing poetry or prose in Paper 2