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25-02-2026
The CBSE Class 10th Science Answer Key 2026 is one of the most searched resources after the completion of the board examination. Students who appeared for the Science exam conducted by the Central Board of Secondary Education eagerly look for the answer key to evaluate their performance and estimate their expected scores before the official results are declared.
In this article, you will find complete details about the CBSE Class 10 Science Answer Key 2026, including unofficial solved PDFs (All Sets), exam analysis, marking scheme, passing criteria, and steps to calculate your probable marks.
The CBSE Class 10 Science Board Exam 2026 is conducted in offline (pen-and-paper) mode. The paper generally carries 80 marks for theory and 20 marks for internal assessment, making a total of 100 marks.
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The CBSE Class 10 Science Question Paper 2026 follows the latest CBSE sample paper format issued by CBSE. This year, the paper is structured in a clearly divided format covering three major branches of Science:
The question paper includes a variety of question types designed to test conceptual understanding and application-based learning.
Students can download the CBSE Class 10th Science Answer Key 2026 PDF (All Sets) once it becomes available on leading education portals.
| QUESTION SET | LINK |
| Question set 1 | Set 1(31/2/1) |
| Question set 2 | Set 2(31/5/2) |
| Question set 3 | Set 3(31/5/3) |
SECTION - A (Biology)
Q. No | Correct Answer | Explanation |
| 1 | (C) Uterus |
Implantation of the fertilized egg (embryo) occurs in the lining of the uterus.
|
| 2 | (D) Budding |
Yeast reproduces asexually through the process of budding.
|
| 3 | (C) Guard cells |
Guard cells control the opening and closing of stomatal pores by changing shape.
|
| 4 | (D)  |
This equation represents anaerobic respiration specifically in human muscle cells.
|
| 5 | (B) DDT |
DDT is a synthetic chemical that does not break down naturally in the environment.
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| 6 | (C) 44+XY |
A human egg (22+X) fertilized by a Y-sperm (22+Y) results in a male zygote (44+XY).
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| 7 | (C) (i), (ii), (iii) and (iv) |
All listed factors contribute to the excessive generation of waste.
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| 8 | (A) |
Assertion & Reason are both true; muscles in the gut lining push food via peristalsis.
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| 9 | (A) |
Assertion & Reason are both true; asexual reproduction creates clones with minor DNA errors.
|
| Part A Answer :10 |
| Identification of Reflex Arc: |
P: Receptor (Heat/Pain receptors in the skin) Q: Sensory Neuron R: Relay Neuron (located in the Spinal Cord) S: Effector (Muscle in the arm) |
| Part B |
Plant Hormones: |
(i) Promote cell division: Cytokinins (ii) Inhibition of growth: Abscisic acid (iii) Detection of light: Auxins (which facilitate phototropism) (iv) Wilting of leaves: Abscisic acid |
Answer 11. Double Circulation in Human Heart |
Double circulation involves the blood passing through the heart twice during one complete cycle through the body:
|
Answer 12. Leaf Structure and Photosynthesis |
(i) P: Chloroplast; Role: It contains chlorophyll, which traps solar energy necessary for the process of photosynthesis. (ii) Balanced Equation for Photosynthesis: |
Answer 13. |
(a) Plastic Bags: Harmful Effect: They are non-biodegradable and cause soil/water pollution or choke animals. Alternatives: Jute bags, paper bags, or cloth bags. (b) Chemicals in Food Chain: How they reach us: Chemicals in soil/water are absorbed by plants (paddy), which are then consumed by humans. Phenomenon: Biological Magnification (Biomagnification). |
Answer 14. Control and Coordination (Adrenaline) |
(a) Gland: Adrenal Gland. Hormone: Adrenaline. (b) Body Responses: Increased heart rate: To supply more oxygen to the muscles. Increased breathing rate: Due to contractions of the diaphragm and rib muscles. |
Answer 15. |
(a) Bowman’s Capsule: A cup-shaped structure at the upper end of a nephron that collects the initial filtrate from the glomerulus. (b) Filtration vs. Excretion: Most of the 180 L of filtrate is reabsorbed by the nephron tubules, leaving only 1-2 L as urine. (c) Excretion: The biological process of removing harmful metabolic wastes from the body. It is necessary to prevent the toxic buildup of substances like urea. OR (c) Similarities (Lungs vs. Kidneys): Both are primary excretory organs and both possess a large surface area for exchange (alveoli in lungs, nephrons in kidneys). |
Answer 16. |
Part (A) Vegetative Propagation: |
(i) Process: Vegetative Propagation. (ii) Advantages: Plants can be grown faster than from seeds, and they are genetically identical to the parent. (iii) Examples: Rose, Grapes, or Potato. (iv) Regeneration Limitation: Complex organisms have specialized tissues and organs; they cannot regrow a whole body from a small piece because their cells are highly differentiated. OR |
Part (B) Post-Fertilization Changes: |
(i) Structure Changes: (a) Zygote: Develops into the Embryo. (b) Ovule: Develops into the Seed. (c) Ovary: Develops into the Fruit. (d) Sepals: Usually wither and fall off. (ii) Germination: The process by which a seed develops into a seedling under appropriate conditions of water, air, and temperature. |
SECTION - B (Chemistry)
Q. No | Correct Answer | Explanation |
| 17 | (D) C4H8 and C5H12 |
C4H8 is an alkene (Butene), while C5H12 is an alkane (Pentane).
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| 18 | (D) Al2O3 |
Aluminum oxide is amphoteric; it reacts with both acids and bases.
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| 19 | (C) The amount of H2 gas evolved is less. |
Acetic acid is a weak acid compared to sulfuric acid, so the reaction is slower.
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| 20 | (B) 2:1 |
Water (H2O) breaks into 2 parts Hydrogen and 1 part Oxygen by volume.
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| 21 | (D) |
CH3COONa is formed from a weak acid and strong base, making it Basic.
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| 22 | (C) C3H8 |
Propane (C3H8) is a saturated hydrocarbon (alkane) and does not undergo addition.
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| 23 | (D) Magnesium and Aluminium |
Both are above Hydrogen in the reactivity series and can displace it from HCl.
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| 24 | (A) |
Assertion & Reason are both true; the reaction of quicklime and water is highly exothermic.
|
SECTION - C (Physics)
Q. No | Correct Answer | Explanation |
| 30 | (A) Converging lens |
A reduced eyeball causes hypermetropia, which is corrected using a convex (converging) lens.
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| 31 | (A) 20 cm |
The focus (f) is 25 cm. For a virtual image in a convex lens, the object must be within the focal length (u<25 cm).
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| 32 | (D) |
Assertion is False, Reason is True. In a strong external field, the needle aligns with that field, not necessarily Earth's North-South.
|
To pass the CBSE Class 10 Science exam:
The answer key helps students:
✔ Estimate their expected board exam score
✔ Identify mistakes and weak areas
✔ Reduce post-exam stress
✔ Prepare better for future competitive exams
However, students should remember that final marks depend on CBSE’s official evaluation process.
The Central Board of Secondary Education is expected to declare the Class 10 results in May 2026 (tentatively). Students can check their results online using their roll number and admit card details.
Also check :
CBSE Class 10 Maths(Standard)Answer key 2026 - All Sets
CBSE Class 10 Maths(Basic)Answer key 2026 - All Sets
Q1. Does CBSE release official answer keys for Class 10 Science?
No, the Central Board of Secondary Education does not officially release answer keys for board exams.
Q2. Where can I download the CBSE Class 10 Science Answer Key 2026 PDF?
You can download unofficial answer keys from trusted education portals after the exam concludes.
Q3. Is the unofficial answer key reliable?
It is prepared by subject experts and teachers, but final marks depend on CBSE’s official evaluation.
Q4. What are the passing marks in CBSE Class 10 Science?
Students need at least 33% aggregate marks to pass.
Q5. When will CBSE Class 10 Result 2026 be declared?
The result is expected in May 2026 (tentative).
The CBSE Class 10th Science Answer Key 2026 (All Sets PDF Download) is a valuable resource for students who want to evaluate their board exam performance immediately after the test. While unofficial answer keys provide a good estimate, students should wait for the official results declared by the Central Board of Secondary Education for final confirmation.
Stay tuned for the latest updates on answer key PDFs, exam analysis, and result announcements.
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