CBSE Class 12 Science Last 100 Days Plan 2027 — PCM and PCB | Padhaao Blog

In short: CBSE has not released the 2027 date sheet yet, but last year's Class 12 theory exams started on February 17. With about 112 days left, this guide gives a 15-week plan from Monday, November 2 to Sunday, February 14 for both PCM and PCB students. It covers verified unit marks for Chemistry, Maths and Biology, the Physics units whose marks I could confirm, and the overlap with JEE Main Session 1 (January 20 to 28, 2027). Watch one risk: JEE Main Session 2 is tentatively April 2 to 7, and last year's CBSE Class 12 papers ran until April 9 or 10, so check your date sheet for clashes.

Last updated: October 28, 2026. Dates will be updated when CBSE publishes the official date sheet.

CBSE Class 12 Science 2027 — Quick Reference

Parameter	Details
Date sheet	Not released as of October 28, 2026. Reports expected it between October 27 and 31
Last year's Class 12 exams	Started February 17, 2026. Ended around April 9 to 10
Physics, Chemistry, Biology	70 theory plus 30 practical
Maths	80 theory plus 20 internal assessment
English Core	80 theory plus 20 internal assessment
Question mix	50% competency-based, 20% select response, 30% constructed response
Passing criteria	33% separately in theory and in practical or internal
Practicals	Expected in January 2027
JEE Main 2027 Session 1	January 20, 21, 22, 23, 24 and 28, 2027
JEE Main 2027 Session 2 (tentative)	April 2 to 7, 2027

Sources: Jagran Josh, NDTV, Aakash, Careers360.

Where the Marks Are: Subject by Subject

Chemistry (70 marks)

Unit marks from the 2026-27 course structure:

Chapter	Marks
Electrochemistry	9
Aldehydes, Ketones and Carboxylic Acids	8
Solutions	7
Chemical Kinetics	7
d and f Block Elements	7
Coordination Compounds	7
Biomolecules	7
Haloalkanes and Haloarenes	6
Alcohols, Phenols and Ethers	6
Amines	6
Total	70

Source: Vedantu course structure 2026-27. Organic chapters (haloalkanes to biomolecules in this list) add up to 33 marks.

Maths (80 marks)

Unit	Marks
Calculus	35
Vectors and 3D Geometry	14
Algebra	10
Relations and Functions	8
Probability	8
Linear Programming	5

See our Maths weightage guide.

Biology (70 marks)

Unit	Marks
Genetics and Evolution	20
Reproduction	16
Biology and Human Welfare	12
Biotechnology	12
Ecology	10

See our Biology weightage guide.

Physics (70 marks)

EdexLive's 2026-27 breakdown reports Electrostatics at 16 marks, the Magnetic Effects of Current and Magnetism block at 17 marks and Electronic Devices at 7 marks (EdexLive). I could confirm only those three units, so check the full unit list in the official CBSE syllabus PDF. Our Physics weightage guide and derivations list cover the rest.

The JEE Main and NEET Overlap

Situation	What to do
JEE Main Session 1: January 20 to 28, 2027	Plan it as a mock-style attempt inside your board prep. Our JEE and boards together guide shows how
Practicals expected in January	Check your school's practical dates against your JEE exam day and city allotment
JEE Main Session 2 tentatively April 2 to 7	Last year CBSE Class 12 ran until April 9 or 10. If 2027 is similar, a clash is possible. Read the CBSE date sheet carefully
NEET aspirants (PCB)	Class 12 NCERT Biology is the base for both. See NEET and boards together

I did not find confirmed NEET 2027 dates, so this plan does not assume them.

The Four Phases (15 Weeks)

Phase	Weeks	Dates	Goal
1. Complete and revise once	1 to 6	Nov 2 to Dec 13	Finish every chapter. Write derivations and reactions by hand
2. Practise by topic	7 to 10	Dec 14 to Jan 10	Numericals, assertion-reason, case-based sets. Start the mistake notebook
3. Full papers and practicals	11 to 13	Jan 11 to Jan 31	Timed full papers. JEE Session 1 week for PCM. Practical exams
4. Final revision	14 to 15	Feb 1 to Feb 14	Derivations, named reactions, diagrams, formulas. Light revision only

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Week-by-Week Plan: Phase 1

This assumes your school has covered a good part of the syllabus. Compress it if you are behind.

Week	Dates	Physics	Chemistry	Maths (PCM)	Biology (PCB)
1	Nov 2 to 8	Electrostatics	Solutions, Electrochemistry	Relations and Functions, Inverse Trigonometry	Reproduction chapters
2	Nov 9 to 15	Current Electricity, Magnetic Effects	Chemical Kinetics, d and f Block	Matrices, Determinants	Principles of Inheritance
3	Nov 16 to 22	EMI and AC, EM Waves	Coordination Compounds, Haloalkanes	Continuity and Differentiability	Molecular Basis of Inheritance, Evolution
4	Nov 23 to 29	Ray Optics, Wave Optics	Alcohols and Ethers, Aldehydes and Ketones	Application of Derivatives	Human Health, Food Production, Microbes
5	Nov 30 to Dec 6	Dual Nature, Atoms, Nuclei, Semiconductors	Amines, Biomolecules	Integrals	Biotechnology chapters
6	Dec 7 to 13	Quick revision of weak derivations	Named reactions revision	Application of Integrals, Differential Equations	Ecology chapters

Week-by-Week Plan: Phases 2 to 4

Week	Dates	Focus
7	Dec 14 to 20	Physics numericals on Electrostatics and Current Electricity. Chemistry numericals: Solutions, Electrochemistry, Kinetics. Maths Calculus sets. Biology genetics problems
8	Dec 21 to 27	Optics numericals and ray diagrams. Organic conversions. Vectors and 3D. Biology diagrams
9	Dec 28 to Jan 3	Case-based and assertion-reason sets in all subjects. English writing formats
10	Jan 4 to 10	Section-wise sample papers. Mark with the official scheme. Begin the mistake notebook review
11	Jan 11 to 17	Full timed papers: Physics and Chemistry. Then Maths or Biology
12	Jan 18 to 24	PCM: JEE Main Session 1 days (Jan 20 to 24) plus a light board revision. PCB: full Biology paper and practical preparation
13	Jan 25 to 31	Reset after JEE day Jan 28. Full papers: English and the remaining subject. Complete practical files
14	Feb 1 to 7	Derivations, reactions, formulas, diagrams. Four short daily slots
15	Feb 8 to 14	Light revision. Stationery, admit card and travel plan. Sleep

Daily Routine (Illustrative)

Time block	Activity
Morning, 1.5 hours	Hardest subject of the day: concepts and derivations
After school, 2 hours	Numericals or problem practice
Evening, 1 hour	Second subject, short revision
Night, 30 minutes	Mistake notebook and tomorrow's plan

The 2026 CBSE Class 12 topper reported 2 to 3 hours of regular daily study (NDTV). That topper was a Commerce student, so treat it as an example of consistency. For Science, 5 to 6 focused hours in this phase is a common target. Quality of practice matters more than the number of hours.

Writing for the Scanner

If CBSE continues On-Screen Marking for Class 12 in 2027, your answer book is read as a scanned image. Practise the habits in our guides on writing answers for on-screen marking and step marking. OSM for 2027 had not been officially confirmed at the time of writing. See what we know.

Common Mistakes in the Last 100 Days

Mistake	Fix
Chasing JEE or NEET at the cost of boards	Boards decide eligibility and fallback options. Use the overlap, do not neglect either
Reading derivations instead of writing them	Write each derivation weekly with all steps
Skipping the practical file	It is 30 marks in Physics, Chemistry and Biology
Leaving Biology diagrams to the end	Practise labelled diagrams from Week 1
Not checking the date sheet for clashes	Compare it with JEE Session 2 and any other exam you plan to take

Frequently Asked Questions

When will the CBSE Class 12 date sheet 2027 be released?

It had not been released as of October 28, 2026. Reports expected it between October 27 and 31. Practical exams are expected in January 2027 and theory in mid-February.

Is 100 days enough for CBSE Class 12 Science?

If you have covered most of the syllabus, yes. This plan gives about 15 weeks. If you are far behind, prioritise high-mark units first, such as Calculus, Electrochemistry and Genetics, and use shorter daily blocks.

How should I plan for JEE Main Session 1 and boards together?

Treat Session 1 (January 20 to 28) as a checkpoint. Do light board revision on exam days, resume full papers after January 28 and keep the practicals in view. Read our JEE Session 1 last 15 days strategy.

Which Chemistry chapters carry the most marks?

Electrochemistry carries 9 marks, Aldehydes, Ketones and Carboxylic Acids 8, and several chapters carry 7. Organic chapters together carry 33 of 70 marks.

Has the Class 12 exam pattern changed for 2027?

No. CBSE said the question paper design and assessment pattern are unchanged for 2026-27, with 50% competency-based questions.

How many practical marks are there?

Thirty marks in Physics, Chemistry and Biology. Maths and English have 20 marks of internal assessment. You must pass theory and practical or internal separately, with 33% in each.

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CBSE Class 12 Science Last 100 Days Plan 2027 — PCM and PCB