Class 10 Science Important Questions by Chapter

Decision guide

What this guide helps you decide

Class 10 Science Important Questions: Study With Understanding is meant to help cbse class 10 science students move from confusion to a clear next step. A useful guide should answer the immediate question, explain the trade-offs, and help the family decide what to do today.

Clarify the student's current class, confidence level, and weakest academic friction point.

Separate popularity, pressure, and prestige from what genuinely helps the child learn.

Choose one practical action the family can take this week.

Use Eduro to turn the decision into a doubt-clearing, revision, or practice session.

How to use these important questions

Treat this as a revision checklist, not a substitute for NCERT. Read the chapter, then attempt each question below from memory before checking the answer. In Science, marks come from precise definitions, correct diagrams, balanced equations, and clear reasoning, so write full answers rather than one-liners.

Chemistry important questions (with answers)

High-frequency questions from Chemical Reactions and Equations, Acids Bases and Salts, Metals and Non-metals, and Carbon and its Compounds.

Why is respiration called an exothermic reaction? Because glucose is oxidised to release energy (heat) the body uses.

Why should a magnesium ribbon be cleaned before burning in air? To remove the protective magnesium oxide layer so it burns easily.

Why does dry HCl gas not change the colour of dry litmus paper? HCl gives H+ ions only in solution; without water it does not ionise.

Why do ionic compounds have high melting points? Strong electrostatic forces of attraction between oppositely charged ions.

Why does carbon form a very large number of compounds? Because of catenation (carbon-carbon bonding) and its tetravalency.

Biology important questions (with answers)

High-frequency questions from Life Processes, Control and Coordination, How do Organisms Reproduce, and Heredity and Evolution.

Why is the small intestine long and highly folded? To give a large surface area for complete absorption of digested food.

What is the role of stomata in a leaf? Exchange of gases (CO2 and O2) and loss of water vapour through transpiration.

What is a reflex arc? The pathway a reflex action follows from receptor to spinal cord to effector, without conscious thought.

How is the sex of a child determined in humans? By the sperm: an X-carrying sperm gives a girl (XX), a Y-carrying sperm gives a boy (XY).

State one advantage of sexual reproduction over asexual reproduction. It produces variations that help a species survive and evolve.

Physics important questions (with answers)

High-frequency questions from Light (Reflection and Refraction), The Human Eye and the Colourful World, Electricity, and Magnetic Effects of Electric Current.

Why does the sky appear blue? Air molecules scatter shorter-wavelength blue light much more than red light.

What is myopia and how is it corrected? Short-sightedness where the image forms in front of the retina; corrected using a concave lens.

Why is tungsten used as the filament of an electric bulb? It has a very high melting point and high resistivity, so it glows without melting.

State Ohm's law. At constant temperature, current through a conductor is directly proportional to the potential difference across it (V = IR).

State the principle of an electric motor. A current-carrying coil placed in a magnetic field experiences a force that makes it rotate.

Revising for the 2026 board exam

In the last few weeks, focus on the questions that carry diagrams and derivations: ray diagrams for lenses and mirrors, the human eye, a neuron, the digestive or excretory system, and circuit diagrams. Practise writing balanced chemical equations and definitions exactly, because these are where students lose easy marks.

Use Eduro to turn mistakes into practice

For any question above, you can ask Eduro to explain the reaction or process, redraw a diagram in simpler steps, compare two confusing concepts, or quiz you before a test. Every wrong answer points to one weak idea, and Eduro helps you fix that idea and practise similar questions.

Use this framework

What an important-question set should test

Chemistry: equation plus observation

Practise balancing equations, identifying reaction types, stating conditions, and describing visible observations such as colour change, gas formation, or precipitate.

Biology: process plus labelled structure

Prepare sequences such as nutrition, respiration, transport, reproduction, and control with the keywords and diagrams that make an answer complete.

Physics: principle plus calculation

Combine definitions and diagrams with formula selection, substitution, SI units, sign conventions, and a final statement that answers the question.

Turn important questions into real revision

1Attempt each question before reading a model answer.
2Underline the command word: define, explain, compare, calculate, or draw.
3Record the missing concept behind every incomplete answer.
4Practise a fresh question from the same concept within 24 hours.

Questions students and parents ask

Are important questions enough for Class 10 Science boards?

No. Important questions are a revision tool, not a substitute for NCERT chapters, activities, diagrams, in-text questions, and sample papers.

Which Class 10 Science chapters need numerical practice?

Electricity and Light require the most regular numerical work. Students should also practise units, formula conditions, circuit or ray diagrams, and interpretation of the result.

How should I write a 3-mark Science answer?

Match the number of distinct points to the marks, use precise NCERT terms, add an equation or labelled diagram when relevant, and avoid repeating the same idea in different words.

Turn the decision into a learning plan

Eduro becomes useful after the decision is made: the student can ask the next doubt, revise the weak chapter, practise at the right level, and keep improving without waiting for the next class.

Start with Eduro