CBSE Class 10 Science: Unit-wise Weightage and a 60-Day Plan

Class 10 Science covers Physics, Chemistry and Biology in a single paper, so it can feel like three subjects at once. Students often revise it chapter by chapter in textbook order, giving every chapter the same time.

The board paper doesn't work that way. Some units carry far more marks than others. If you know the split, you can plan revision around it.

This guide shows the unit-wise weightage, how the 13 NCERT chapters map to each unit, and a 60-day plan from mid-December to mid-February.

The unit-wise weightage

The Class 10 Science exam has 80 marks for the theory paper and 20 marks for internal assessment. In the recent CBSE curriculum, the 80 theory marks are split by unit like this:

Check the current curriculum. CBSE can revise this split from one session to the next. Before you plan, download the Science curriculum and the latest sample paper for your session from cbseacademic.nic.in.

CBSE gives marks per unit, not per chapter. Lists of "chapter-wise marks" you see online are estimates. Use the unit weightage, then give each chapter time based on how many chapters share that unit.

How the 13 NCERT chapters map to the units

These are the chapters of the current rationalised NCERT textbook.

Chemical Substances – Nature and Behaviour (25)

• Chemical Reactions and Equations
• Acids, Bases and Salts
• Metals and Non-metals
• Carbon and its Compounds

World of Living (25)

• Life Processes
• Control and Coordination
• How do Organisms Reproduce?
• Heredity

Natural Phenomena (12)

• Light – Reflection and Refraction
• The Human Eye and the Colourful World

Effects of Current (13)

• Electricity
• Magnetic Effects of Electric Current

Natural Resources (5)

• Our Environment

What this tells you

• Chemistry and Biology together are 50 of 80 marks. Eight chapters carry them, so each of those chapters deserves real time.
• Physics is 25 marks across four chapters. Electricity is numerical-heavy and very scoring once practised.
• Our Environment is short. One careful revision and the NCERT exercises are usually enough.

Before day 1: set up

Spend one evening getting ready:

1. Download the latest sample paper and marking scheme from cbseacademic.nic.in.
2. Make a one-page tracker with the 13 chapters and three columns: Round 1, Round 2, Paper mistakes.
3. Start a mistakes notebook. Every wrong answer from a test goes in, with the correct method in a line or two.

The 60-day plan

This plan assumes about 75–90 minutes of Science on most days, alongside other subjects.

Days 1–25: First round, weighted by marks

For every chapter:

• Re-read the NCERT chapter and mark definitions, reactions and solved examples.
• Answer all in-text and back-exercise questions.
• Redraw every labelled diagram once from memory.
• Finish with 10 previous years' board questions on that chapter.

Our guide to using NCERT the right way explains how to read and annotate each chapter.

Days 26–45: Second round plus papers

• Revise each unit quickly from your own notes and the mistakes notebook.
• Go back to the textbook only for chapters marked weak on your tracker.
• Two full papers a week. Sit each one in a single three-hour sitting with a timer.
• Mark every paper against the CBSE marking scheme, step by step.

Days 46–55: Timed papers and weak spots

• Three full papers a week.
• After each paper, spend an hour on the weakest chapter it exposed.
• Read the mistakes notebook from start to finish once a week.

Days 56–60: Light revision

• No new material.
• Revise only diagrams, reactions, formulas and the mistakes notebook.
• One last paper, then rest. Sleep matters more than one extra late night.

Unit-by-unit tips

Chemistry

• Write every reaction balanced, with states of matter where the question asks for them.
• Learn the pH scale and indicator colour changes in Acids, Bases and Salts.
• In Carbon and its Compounds, practise naming and drawing structures until they are automatic.

Biology

• Diagrams carry marks: the human heart, the nephron, the neuron, the human brain and plant structures are worth practising.
• Use the exact NCERT terms in answers about processes such as respiration, excretion and reproduction.
• In Heredity, practise the monohybrid cross with a clear Punnett square.

Physics

• In Electricity, practise series and parallel circuits until finding equivalent resistance is quick.
• In Light, fix the sign convention before using the mirror and lens formulas.
• Always write units with final answers.

On exam day: use the reading time

CBSE gives 15 minutes of reading time before you start writing. Use it well:

• Read the whole paper once.
• Mark the questions you are most confident about.
• Note the case-based questions, which take longer.
• Plan roughly how long each section should take.

A note on the second board exam

From 2026, CBSE gives Class 10 students an optional second exam later in the year to improve scores in a limited number of subjects. Treat it as a safety net, not a plan. Check the latest CBSE circular for the rules that apply to your batch. For a longer timeline across all subjects, see our 90-day Class 10 revision plan.

Get structured support

If the same chapters keep costing marks in your papers, feedback on each answer helps more than extra hours. Our Class 10 Science programme includes weekly board-pattern tests with step-wise marking. For a focused final push, the Board Exam Crash Course runs before the boards with full revision and timed mock papers.

Next step: moving into Class 11 after the boards? ASCAT, our scholarship-cum-admission test places you in the right batch and can earn a tuition scholarship.