CBSE Class 10 Science Board Paper Set 2 — MCQs with Answers
Original paper · CBSE patternWritten by our subject team, not a reprint of an official sample paper.
- Questions
- 20
- Time
- 25 min
- Marking
- +1, no negative marking
- Mix
- 8 Easy · 8 Medium · 4 Hard
Board Paper Set 2 — CBSE Class 10 Science is a full 20-question objective paper for Class 10 Science, written in the CBSE board pattern and marked the way the board marks: +1 for a correct answer and 0 for a wrong one — no negative marking, exactly like the real board paper. It follows Section A of a real CBSE paper: Q1–Q16 are single-correct MCQs, Q17–Q18 are case-based questions built on a short source, and Q19–Q20 are assertion–reason items using the board's own four option strings.
Difficulty is 8 Easy · 8 Medium · 4 Hard, weighted the way the board weights Section A. You get 25 minutes — about 75 seconds a question, the pace the real paper demands. 8 of the questions are solved in full below, with the correct option and a worked explanation for each; the remaining 12 are timed and scored when you sign in free.
From 2026-27 CBSE Class 10 has two board exams a year: the first around 15 February – 10 March 2027 is compulsory, and an optional improvement exam in May 2027 lets you re-attempt up to three subjects with the better score counting. That gives you two genuine attempts — and makes timed practice between February and May worth far more than it used to be.
8 solved questions from this paper
Answer and worked explanation shown for each. The remaining 12 are timed and scored when you sign in free.
- Q1Easy
Quicklime reacts vigorously with water as CaO + H₂O → Ca(OH)₂, and the vessel becomes hot. This reaction is best described as:
A.an endothermic decomposition reactionB.an exothermic combination reaction✓ CorrectC.an endothermic combination reactionD.an exothermic displacement reactionAnswer: B. an exothermic combination reaction
Explanation: Two reactants join to form a single product, calcium hydroxide, which makes it a combination reaction. Because the vessel becomes hot, heat is released to the surroundings, so the change is exothermic. An endothermic change would instead make the vessel feel cold, as happens when barium hydroxide reacts with ammonium chloride.
- Q2Easy
Which of the following salts gives a basic solution when dissolved in water?
A.Sodium carbonate✓ CorrectB.Sodium chlorideC.Ammonium chlorideD.Sodium sulphateAnswer: A. Sodium carbonate
Explanation: The nature of a salt solution follows from the acid and base that formed it. Sodium carbonate comes from a strong base, sodium hydroxide, and a weak acid, carbonic acid, so its solution is basic with a pH above 7. Sodium chloride and sodium sulphate come from a strong acid and a strong base and are neutral, while ammonium chloride, from a strong acid and a weak base, gives an acidic solution.
- Q3Easy
Which of the following non-metals is a good conductor of electricity?
A.SulphurB.PhosphorusC.Graphite✓ CorrectD.IodineAnswer: C. Graphite
Explanation: In graphite each carbon atom is bonded to only three others, which leaves one electron per atom free to move through the layers and carry current. This makes graphite the well-known exception to the rule that non-metals are insulators, and it is used for electrodes. Sulphur, phosphorus and iodine have all their valence electrons locked in bonds and do not conduct.
- Q4Medium
In the reaction CuO + H₂ → Cu + H₂O, the substance that has been oxidised is:
A.CuOB.CuC.H₂OD.H₂✓ CorrectAnswer: D. H₂
Explanation: Oxidation is the gain of oxygen and reduction is its loss. Hydrogen picks up oxygen to become water, so hydrogen is oxidised, while copper oxide loses its oxygen and is reduced to copper. Naming copper oxide as the oxidised species is the standard confusion; it acts as the oxidising agent precisely because it is itself reduced.
- Q5Medium
Aluminium is a reactive metal, yet aluminium utensils do not corrode away in air. The reason is that:
A.aluminium is less reactive than ironB.a thin, tightly held layer of aluminium oxide covers the surface and protects the metal beneath✓ CorrectC.aluminium does not react with oxygen at allD.aluminium reacts with the nitrogen of air rather than with its oxygenAnswer: B. a thin, tightly held layer of aluminium oxide covers the surface and protects the metal beneath
Explanation: Aluminium reacts readily with air, but the oxide formed clings to the surface as a continuous film that keeps fresh oxygen and moisture away from the metal underneath. This is why aluminium is used for window frames and cooking vessels. Iron, despite being less reactive than aluminium, keeps corroding because its rust flakes away and exposes fresh metal instead of sealing the surface.
- Q6Medium
A person is able to walk in a straight line but cannot ride a bicycle without falling over. The part of the brain most likely to be affected is the:
A.CerebrumB.Cerebellum✓ CorrectC.Medulla oblongataD.PonsAnswer: B. Cerebellum
Explanation: Precision of voluntary movement and the maintenance of posture and balance are controlled by the cerebellum, which is exactly what riding a bicycle demands. The cerebrum handles thinking, memory and voluntary decisions, and the medulla oblongata looks after involuntary actions such as heartbeat, breathing and vomiting, so damage to those would show quite different symptoms.
- Q7Hard
The number of structural isomers possible for the compound with molecular formula C₄H₁₀ is:
A.4B.3C.5D.2✓ CorrectAnswer: D. 2
Explanation: Four carbon atoms can be arranged either as a straight chain, giving n-butane, or as a three-carbon chain with a methyl branch on the middle carbon, giving isobutane. No other skeleton is possible, because putting the branch on an end carbon simply recreates the straight chain, so there are two isomers. Learners often count such repeats separately and arrive at a larger number.
- Q8Hard
In pea plants, round seed shape (R) is dominant over wrinkled seed shape (r). A round-seeded plant is crossed with a wrinkled-seeded plant, and about half the offspring have wrinkled seeds. The genotype of the round-seeded parent is:
A.RRB.Rr✓ CorrectC.rrD.either RR or RrAnswer: B. Rr
Explanation: The wrinkled parent must be rr and can pass on only r, so any wrinkled offspring must have received an r from the round parent as well. A round parent that produces r gametes has to be Rr, and the cross Rr × rr gives half round and half wrinkled offspring, matching the result. A pure RR parent would give only Rr offspring, all of them round, so no wrinkled seeds could appear.
Sit the full paper — free
All 20 questions on a 25-minute timer, scored automatically, with a worked solution for every one — including the 12 not shown above. Sign in with Google — no card needed.
Attempt this paper free →More Class 10 Science board papers
- Board Paper — 31 questions
- Board Paper Set 1 — 20 questions
- Board Paper Set 2 — you are here
- Board Paper Set 3 — 20 questions
Prefer chapter-by-chapter revision first? Class 10 Science notes & chapter MCQs →
Questions students ask about this paper
Is this an official CBSE sample paper?
No — and that is deliberate. This is an original paper written in the CBSE board pattern by our subject team, not a copy of CBSE's official Sample Question Paper. It means you get fresh questions you have not already seen on a dozen other sites, with instant scoring and worked solutions rather than a PDF.
How is this Class 10 Science paper marked?
+1 for a correct answer and 0 for a wrong one — no negative marking, exactly like the real board paper. So attempt every question — there is no penalty for a wrong answer on a board paper, and leaving a question blank can only cost you.
How long should this paper take?
25 minutes for 20 questions, roughly 75 seconds each. The timer runs whether or not you are watching it, which is the point: board marks are lost to pacing at least as often as to gaps in knowledge.
Do I need to pay to attempt it?
No. Sign in free with Google and the full paper opens with a live timer, automatic scoring and a worked solution for every question — including the ones not shown on this page.
Does the May 2027 improvement exam change how I should practise?
It raises the value of timed practice. Because the better of your two scores counts, a February attempt that goes badly is no longer final — but only if you know precisely which topics cost you the marks. A scored full-length paper tells you that; re-reading the chapter does not.