Important Questions for Class 10 Science: Chapter-Wise List with Answers, Concepts and Formulas
Important questions for Class 10 Science are one of the highest-scoring subjects in the CBSE board exam, but only when preparation is built around the questions examiners ask year after year. This page brings together Important questions for Class 10 Science from Physics, Chemistry and Biology, along with the key concepts, definitions and formulas you need to answer them confidently. Whether you are revising a single chapter the night before a test or doing a full board-exam revision, use this guide from MyClass24 as a structured checklist rather than a one-time read.
Why Practising Important Questions for Class 10 Science Matters
CBSE question papers are largely predictable in the concepts they test, even though the wording of each question changes every year. A student who has only read the NCERT textbook once often struggles to convert that reading into exam-ready answers. Practising a curated list of important questions for Class 10 Science does three things: it highlights which topics carry the highest weightage, it forces you to recall formulas and definitions in your own words, and it trains you to write answers within the word and mark limits set by the board. Numericals from Electricity, Light, and mole-based Chemistry problems, along with diagram-based questions from Life Processes and Control and Coordination, are repeated almost every year in some form, which is exactly why this list gives them extra focus.
How to Use This Preparation List
Go chapter by chapter rather than jumping randomly between Physics, Chemistry and Biology. For each chapter, first revise the formulas and key terms in the tables below, then attempt the listed questions without looking at your notes. Write the numerical answers step by step, since CBSE awards marks for correct method even when the final answer has a small error. Keep a separate notebook for formulas so that a day before the exam you only need to revise that one page instead of the entire textbook.
Physics: Important Questions for Class 10 Science
Chapter: Light — Reflection and Refraction
This chapter is a guaranteed source of both theory and numerical questions. Focus on the sign convention, the mirror formula, and ray diagrams for convex and concave mirrors and lenses.
Derive the mirror formula and define linear magnification produced by a spherical mirror.
An object is placed at a distance of 25 cm from a concave mirror of focal length 15 cm. Find the position and nature of the image.
Why does the sky appear blue and why do stars twinkle? Explain using the concept of scattering of light.
Draw a ray diagram to show the formation of an image by a convex lens when the object is placed between the optical centre and the focus.
Term | Formula / Rule |
Mirror formula | 1/v + 1/u = 1/f |
Magnification (mirror) | m = -v/u = h'/h |
Lens formula | 1/v - 1/u = 1/f |
Magnification (lens) | m = v/u = h'/h |
Power of a lens | P = 1/f (f in metres); unit: dioptre (D) |
Refractive index | n = speed of light in vacuum / speed of light in medium |
Chapter: The Human Eye and the Colourful World
Common questions test the defects of vision and their correction, along with everyday optical phenomena.
What is myopia? State its causes and the type of lens used to correct it.
Explain why the sun appears reddish at sunrise and sunset with the help of a diagram.
Chapter: Electricity
Electricity questions dominate the numerical section of the Physics paper, so mastering Ohm's law, resistance combinations and power formulas is essential.
State Ohm's law and describe an experiment to verify it.
Two resistors of 4 ohm and 6 ohm are connected first in series and then in parallel. Calculate the equivalent resistance in each case.
Why is the heating element of an electric iron made of an alloy rather than a pure metal?
Calculate the electrical energy consumed by a 60 W bulb used for 6 hours daily over 30 days, in kWh.
Quantity | Formula |
Ohm's law | V = IR |
Resistors in series | R = R1 + R2 + R3 |
Resistors in parallel | 1/R = 1/R1 + 1/R2 + 1/R3 |
Electrical power | P = VI = I²R = V²/R |
Electrical energy | E = P x t (measured in kWh for billing) |
Resistance of a conductor | R = pL/A (p = resistivity, L = length, A = area) |
Chapter: Magnetic Effects of Electric Current
This chapter connects electricity with magnetism, and diagram-based questions on the working of an electric motor or generator are frequently asked.
State the right-hand thumb rule and Fleming's left-hand rule, and explain what each is used for.
With a labelled diagram, explain the working principle of an electric generator.
Chapter: Sources of Energy
Differentiate between renewable and non-renewable sources of energy with two examples of each.
What are the limitations of extracting energy from the wind and from tides?
Chemistry: Important Questions for Class 10 Science
Chapter: Chemical Reactions and Equations
This is the first chapter in the Chemistry unit and questions here test whether you can identify and balance different types of reactions.
Balance the following equation and identify the type of reaction: Fe + H2O -> Fe3O4 + H2.
What happens when a piece of zinc is added to a solution of copper sulphate? Write the balanced chemical equation.
Why should a magnesium ribbon be cleaned before burning it in air? What type of reaction takes place when it burns?
Type of Reaction | General Form / Example |
Combination | A + B -> AB (e.g. CaO + H2O -> Ca(OH)2) |
Decomposition | AB -> A + B (e.g. CaCO3 -> CaO + CO2) |
Displacement | A + BC -> AC + B (e.g. Zn + CuSO4 -> ZnSO4 + Cu) |
Double displacement | AB + CD -> AD + CB (e.g. Na2SO4 + BaCl2 -> BaSO4 + NaCl) |
Oxidation and reduction | Oxidation: gain of oxygen/loss of hydrogen; Reduction: opposite |
Chapter: Acids, Bases and Salts
Why does an aqueous solution of an acid conduct electricity while a solution of an acid in a non-polar solvent like kerosene does not?
What is the pH of a solution and how does it change when water is added to it?
Explain the preparation and one use each of washing soda and baking soda.
Common Salt | Chemical Formula / Use |
Baking soda | NaHCO3 — used in antacids and as a mild disinfectant |
Washing soda | Na2CO3.10H2O — used in the glass and paper industry |
Bleaching powder | CaOCl2 — used for bleaching and disinfecting water |
Plaster of Paris | CaSO4.1/2H2O — used to set fractured bones |
Chapter: Metals and Non-metals
Explain the process of electrolytic refining of a metal with a labelled diagram.
Why are ionic compounds usually solid, hard and have high melting points?
Arrange the following metals in order of their reactivity, based on displacement reactions: Zn, Fe, Cu, Mg, Ag.
Reactivity Series (Most to Least Reactive) | Behaviour |
K, Na, Ca, Mg, Al | React vigorously with water and dilute acids |
Zn, Fe, Pb | React moderately with dilute acids, slowly with water |
Cu, Ag, Au | Do not react with dilute acids; found in free state |
Chapter: Carbon and Its Compounds
Why does carbon form covalent bonds rather than ionic bonds in most of its compounds?
What is a homologous series? Give the general formula for alkanes, alkenes and alkynes.
Differentiate between saturated and unsaturated hydrocarbons, giving one example of each.
Functional Group | Example Compound |
Alcohol (-OH) | Ethanol, C2H5OH |
Carboxylic acid (-COOH) | Acetic acid, CH3COOH |
Aldehyde (-CHO) | Ethanal, CH3CHO |
Ketone (-CO-) | Propanone, CH3COCH3 |
Chapter: Periodic Classification of Elements
State Mendeleev's periodic law and mention one limitation of his classification.
How does atomic size vary across a period and down a group in the modern periodic table? Explain with reasons.
Biology: Important Questions for Class 10 Science
Chapter: Life Processes
Diagram-based and definition-based questions from this chapter appear almost every year, especially on nutrition, respiration and transportation.
Draw a labelled diagram of the human alimentary canal and describe the role of bile in digestion.
Differentiate between aerobic and anaerobic respiration with one example of each.
Explain double circulation in humans and state why it is necessary.
Concept | Key Point |
Autotrophic nutrition | Organism prepares its own food, e.g. green plants via photosynthesis |
Heterotrophic nutrition | Organism depends on others for food, e.g. animals and fungi |
Aerobic respiration | Glucose + O2 -> CO2 + H2O + Energy (in mitochondria) |
Anaerobic respiration | Glucose -> Alcohol/Lactic acid + Energy (without oxygen) |
Chapter: Control and Coordination
Draw a labelled diagram of a neuron and explain how a nerve impulse travels through it.
What is the difference between the nervous system and the hormonal (endocrine) system in coordinating body functions?
Chapter: How Do Organisms Reproduce?
Describe binary fission and budding as modes of asexual reproduction, with one example of each.
What is the role of the placenta in human reproduction?
Chapter: Heredity and Evolution
State Mendel's law of dominance and explain it using a monohybrid cross between a tall and a dwarf pea plant.
How is the sex of a child determined in humans? Explain with the help of a cross showing the possible combinations.
Mendel's Cross | Genotype Ratio | Phenotype Ratio |
Monohybrid cross (Tt x Tt) | 1 TT : 2 Tt : 1 tt | 3 Tall : 1 Dwarf |
Dihybrid cross (RrYy x RrYy) | 9:3:3:1 combinations | 9:3:3:1 |
Chapter: Our Environment
What is a food chain and a food web? Explain the flow of energy through a food chain with an example.
Why is biological magnification a matter of concern for human health?
Quick Revision Table: Key Formulas Across Class 10 Science
Use this consolidated table for a last-minute revision of the most exam-relevant formulas from Physics and Chemistry.
Chapter | Formula |
Light | 1/v + 1/u = 1/f (mirror); 1/v - 1/u = 1/f (lens) |
Electricity | V = IR; P = VI; E = P x t |
Resistance | R = pL/A |
Refractive index | n = c/v |
Power of lens | P = 1/f |
Mole concept | Number of moles = Given mass / Molar mass |
Tips to Score Full Marks in Class 10 Science
Always write balanced chemical equations with correct state symbols (s, l, g, aq).
For numericals, write the given data, the formula used, the substitution of values, and the final answer with correct units — CBSE awards step-wise marks.
Practise all diagrams from Life Processes, Control and Coordination, Electricity and the Human Eye, since well-labelled diagrams often carry direct marks.
Revise definitions in exactly the way NCERT states them, since board evaluators match key terms while checking answer scripts.
Attempt at least one previous year's question paper and one sample paper under timed conditions before the final exam.
Conclusion
Scoring well in Class 10 Science comes down to consistent revision of concepts, formulas and diagrams rather than last-minute cramming. Use this list of important questions for Class 10 Science alongside your NCERT textbook to identify weak chapters early and strengthen them chapter by chapter. For more chapter-wise notes, solved numericals and practice papers for Physics, Chemistry and Biology, keep visiting MyClass24 and make this your one-stop preparation companion for the CBSE Class 10 board exam.