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Important Questions for CBSE Class 8 – Subject-Wise Guide

Class 8 is the year when school syllabi quietly get harder. Maths moves from arithmetic into algebraic generalisation, Science splits properly into Physics, Chemistry, and Biology strands, and Social Science starts asking "why" instead of just "what." Students who sail through Class 6–7 on memory alone often hit a wall here, because Class 8 question papers reward understanding over recall.

This guide pulls together the most exam-relevant Important questions for Maths, Science, Social Science, and English, organised chapter-by-chapter, the way most CBSE and state board papers are actually set. Instead of generic "revise everything" advice, you'll find the specific question types that appear year after year, why students lose marks on them, and how to approach each one. Also, solve questions from NCERT with the help of NCERT Solution for class 8 and NCERT exemplar solutions for class 8.

Important Questions for Class 8 – Subject-wise

How Class 8 Exams Are Actually Weighted

Before jumping into subject questions, it helps to know where marks are concentrated. Most Class 8 annual papers follow a fairly predictable pattern across boards:

Keep this table in mind — it explains why the "important questions" below are weighted toward short and long-answer formats rather than just one-liners.

Mathematics: Chapter-Wise Important Questions

Class 8 Maths (NCERT and most state boards) covers Rational Numbers, Linear Equations, Understanding Quadrilaterals, Practical Geometry, Data Handling, Squares and Square Roots, Cubes and Cube Roots, Algebraic Expressions and Identities, Mensuration, Exponents and Powers, Direct and Inverse Proportions, Factorisation, and Introduction to Graphs.

Rational Numbers

This chapter is deceptively simple — students know the rules but forget to apply them under pressure.

• State and verify the closure property of rational numbers under addition and multiplication, using two negative rational numbers as examples.

• Find the rational number that lies exactly midway between two given rational numbers, such as −3/5 and 4/7.

• Represent a rational number like −7/3 on a number line, and explain the method used to locate fractional points accurately.

• If a rational number's additive inverse equals its multiplicative inverse, find the number (this tests whether students confuse the two inverse concepts).

Linear Equations in One Variable

Word problems dominate this chapter, and most marks are lost in translating English into algebra, not in solving the equation itself.

• A number decreases by 7 when 3/5 of it is subtracted from itself; find the number (classic transposition problem).

• The digits of a two-digit number differ by 3. If the digits are interchanged and the resulting number is added to the original, the sum is 143. Find the number.

• Sum of three consecutive multiples of 8 is 888. Find the multiples (tests setting up variables correctly).

• A father's age is three times his son's age. Ten years later, he will be twice his son's age. Find their present ages.

Understanding Quadrilaterals

• Prove that the sum of all exterior angles of any polygon, formed by producing the sides in order, is 360°.

• ABCD is a parallelogram. Find the measure of angle B if angle A is 70° more than twice angle B (angle sum + parallelogram property combined).

• Distinguish between a rhombus and a square using their diagonal properties — this comparison appears almost every year in some form.

Squares, Square Roots, Cubes, and Cube Roots

Algebraic Expressions, Identities, and Factorisation

• Using a suitable identity, find the value of 297 × 303 without direct multiplication (tests application of (a+b)(a−b)).

• Factorise: 4x² + 12xy + 9y² (recognising a perfect square trinomial).

• Divide the polynomial 6x³ + 11x² − 39x + 20 by (3x − 4) using long division of polynomials.

• Find the product (2x − 1)(2x + 1)(4x² + 1) and identify which identity simplifies the calculation.

Mensuration

This chapter is where diagrams matter as much as formulas.

• Find the area of a trapezium whose parallel sides are 1 m and 1.2 m, with the distance between them being 0.8 m.

• A cuboid is 12 cm long, 9 cm wide, and the total surface area is 360 cm². Find its height (working backward from a formula, common in HOTS questions).

• How much canvas is needed for a conical tent of base radius 6 m and height 8 m, given canvas costs ₹100 per sq m? (combines slant height calculation with cost application).

Exponents, Direct/Inverse Proportions, and Graphs

• Express 0.000000000947 in standard form and explain why negative exponents are used.

• If 36 men can complete a piece of work in 15 days, how many men are needed to finish it in 9 days? (inverse proportion application).

• Plot the points (2, 3) and (−1, −2) on a graph and find the equation of the line passing through them — graph-reading questions are increasingly common in newer papers.

Science: Chapter-Wise Important Questions

Class 8 Science covers Crop Production, Microorganisms, Synthetic Fibres, Materials, Coal and Petroleum, Combustion, Conservation of Plants and Animals, Cell Structure, Reproduction in Animals, Force and Pressure, Friction, Sound, Chemical Effects of Current, Light, Stars and the Solar System, and Pollution.

Physics Topics

• Explain Newton's idea connecting force and motion using the example of a moving ball gradually slowing down due to friction.

• Why do we sometimes hear a thunder sound a few seconds after seeing the lightning flash? (tests understanding of sound vs light speed, a frequently asked HOTS question).

• Draw a labelled diagram showing the formation of an image by a plane mirror and state its characteristics.

Chemistry Topics

• Why should we avoid the use of synthetic detergents for washing clothes near a river or pond? (Combustion/pollution chapter — environment-linked questions are high-yield).

• Differentiate between a fuel's calorific value and the term "ideal fuel," and name two characteristics of an ideal fuel.

• Explain why coal and petroleum are called fossil fuels, and why they are non-renewable.

• What happens when a magnesium ribbon burns in air? Write the word equation and explain why this reaction releases a dazzling white light.

• Define rusting and corrosion. Suggest two methods to prevent the rusting of iron objects used in daily life.

Biology Topics

This is usually the highest-scoring section if students focus on diagrams and labelled processes.

• Draw a neat, labelled diagram of an animal cell and a plant cell, and list three structural differences between them.

• Explain binary fission and budding as modes of asexual reproduction, with one example organism for each.

• What is metamorphosis? Describe the life cycle of a frog, mentioning each stage in correct sequence.

• Why are some microorganisms called "friendly" while others are harmful? Give two examples of each category with their use or harm explained.

• Explain the role of nitrogen-fixing bacteria in maintaining soil fertility, and name the process by which they convert atmospheric nitrogen.

• Describe three ways in which human activities are leading to the depletion of forest cover, and explain why conserving the Red Data Book species matters.

Agriculture and Environment

• Explain the difference between manure and fertilisers, listing one advantage of each.

• What is crop rotation, and how does growing a leguminous crop after a cereal crop benefit the soil?

• Describe the process of pollination and explain why some plants depend on insects for it.

Social Science: History, Civics, and Geography

Social Science is often underprepared because students assume it's "just reading," but boards now ask source-based, map-based, and reasoning questions heavily.

History — How, When, and Where & Colonial India

• Explain the system of indentured labour. Why did Indian labourers migrate to colonies like Mauritius, Fiji, and the West Indies?

• How did the British policy of deindustrialisation affect Indian handicrafts and traditional industries during the 19th century?

• Why is the period after 1857 often described as the beginning of "direct Crown rule" in India, and what changes did it bring administratively?

Civics — The Indian Constitution and Democracy

• Why is the Constitution often called the "supreme law" of the land? Explain with reference to the Fundamental Rights it guarantees.

• Distinguish between the Legislature, Executive, and Judiciary, and explain why separation of powers is important in a democracy.

• What is the Right to Constitutional Remedies, and why is Dr. B.R. Ambedkar's description of it as the "heart and soul" of the Constitution significant?

• Explain the difference between a unitary and a federal system of government, using India as an example of the latter.

• Why do marginalised communities sometimes need special safeguards under the law? Illustrate using one example from the chapter on Marginalisation.

• What is public interest litigation (PIL), and how has it strengthened the role of the judiciary in protecting citizens' rights?

Geography — Resources, Land, and Industries

• Why is water considered a renewable resource in theory but is becoming scarce in practice? Suggest two conservation measures.

• Explain the difference between agglomeration and dispersal of industries, and the factors influencing the location of the cotton textile industry in India.

• What is meant by "human resource," and why is investment in education and health considered investment in human capital?

English: Grammar, Literature, and Writing Skills

English question papers reward structure as much as content. The questions below reflect the format most frequently tested.

Grammar — High-Frequency Areas

• Rewrite the sentence in passive voice: "The committee will announce the results by Friday."

• Change into indirect speech: "Have you finished your homework?" the teacher asked the students.

• Fill in the blanks with appropriate modals: "You ___ apologise to her; it was your mistake." (testing obligation vs suggestion).

• Combine the following sentences using an appropriate connector: "She was tired. She finished the project on time."

Literature — Prose and Poetry Comprehension

Most boards test literature through unseen passage analysis as well as questions from the prescribed reader. Common question types include:

• Reference-to-context questions that ask students to identify the speaker, the situation, and the meaning of a quoted line.

• Character-based questions analysing motivations and changes in a character across the story (commonly asked for chapters like "The Best Christmas Present in the World" or "The Tsunami" type narratives, depending on the board's prescribed book).

• Theme-based long answers asking students to connect the central message of a poem or story to real life — for instance, questions on courage, environmental responsibility, or human relationships frequently appear as 4–5 mark answers.

• Poetic device identification: locating and explaining the use of simile, personification, or repetition within a given stanza.

Writing Skills

• Write a formal letter to the editor of a newspaper expressing concern about increasing noise pollution in your locality.

• Draft a notice for your school notice board informing students about an upcoming inter-house debate competition.

• Write a short story in about 150 words that ends with the line: "...and that is how I learned the value of honesty."

A Smarter Way to Revise These Questions

Simply reading through a list of important questions rarely converts into exam marks. A more effective approach, used by toppers across subjects, looks like this:

1. Sort questions by chapter weightage first, not by how recently you studied them. Chapters like Algebraic Identities, Cell Structure, the Indian Constitution, and Tenses/Voice tend to appear in some form every year — prioritise these.

2. Practice the "why" behind every formula or rule, since most Class 8 papers now include at least one HOTS question per chapter that tests application rather than recall.

3. Write answers, don't just read them. For Social Science and English especially, the difference between a 3-mark and a 5-mark answer is almost always structure — clear points, examples, and a conclusion — not extra facts.

4. Use diagrams wherever the question allows, particularly in Biology (cell structure, life cycles) and Physics (mirror images, force diagrams), since labelled diagrams often carry dedicated marks independent of the written explanation.

5. Revisit map and graph-based questions separately, as these are frequently skipped during regular revision but appear consistently in Geography and Maths papers.

Used this way, the question sets above aren't just a revision checklist — they map directly onto how Class 8 papers are actually designed, chapter by chapter, across Maths, Science, Social Science, and English.