CBSE Class 10 Science Answer Key 2025 OUT - Check Now

Class 10 Science 2025 Answer Key: The CBSE Class 10 Science Exam 2025 was held on February 20, 2025, at various centers across the country. As per student feedback, the paper was moderate in difficulty, with a mix of theory-based, numerical, and application-based questions. Some students found the exam lengthy, especially the case study and reasoning-based sections, which required detailed explanations and time management.

To assist students in verifying their responses and evaluating their performance, we have provided the Answer Key Science Class 10 along with NCERT Solution references. This answer key and NCERT solutions serve as valuable resources. To assist students in verifying their responses and evaluating their performance, we have provided the Answer Key Science Class 10 along with NCERT Solutions references.

 CBSE Class 10 Science Answer Key 2025

The CBSE Answer Key Science Class 10 2025 consists of a total of 39 questions, divided into different sections based on question type and difficulty level. The paper is designed to test students' understanding of theoretical concepts, numerical applications, and case-based scenarios.

Students are given 3 hours (180 minutes) to complete the exam. Additionally, 15 minutes of reading time is provided before the start of the exam, during which students can go through the question paper but are not allowed to write. Proper time management is crucial, as some sections require detailed explanations and calculations.

CBSE Class 10 Science Answer Key 2025 PDF Download

The Class 10 Science Board Paper 2025 Answer Key is an essential resource for students who wish to evaluate their performance after appearing for their Science exam. The answer key provides the correct answers to all the questions asked in the exam, which allows students to compare their responses and gain a better understanding of how well they performed.

The Class 10 Science Answer Key 2025 will be available in multiple sets, such as Set 1, Set 2, and Set 3, to match the different question paper variations. By downloading the PDF of the answer key, students can easily check their answers and predict their scores, making it a valuable tool for self-assessment.

CBSE Class 10 Science Question Paper with Answers

SECTION-A

In this section, Question Nos. 1 to 20 are Multiple-Choice Questions.

1. In the following experimental setup of electrolysis of water, if P and Q are the gases collected in the test tubes enclosing the electrodes R and S, then select the option/options in which the matching is correct:

(i) P-Oxygen gas, R-Anode

(ii) P-Hydrogen gas, R-Cathode

(iii) Q-Hydrogen gas, S-Cathode

(iv) Q-Oxygen gas, S-Anode

(A) (i) and (ii)

(B) (iii) and (iv)

(C) (i) and (iii)

(D) (ii) and (iv)

Ans: (C) (i) and (iii)

2. You have three aqueous solutions A, B and C as given below:

A - Potassium nitrate

B - Ammonium chloride

C - Sodium carbonate

The ascending order of the pH of these solutions is:

(A) A<B<C

(B) B<C<A

(C) C<A<B

(D) B<A<C

Ans: (B) B<C<A

3. Select from the following a statement which is not true about burning of magnesium ribbon in air:

(A) It burns with a dazzling white flame.

(B) A white powder is formed on burning.

(C) It is an endothermic reaction.

(D) It is an example of a combination reaction.

Ans: (C) It is an endothermic reaction.

Important Questions on Light Refraction and Reflection

Q1. List four characteristics of the images formed by plane mirrors. (Delhi 2015, AI2011)

Ans:

1. Virtual and Erect: The image formed is always virtual and upright.
2. Same Size as the Object: The image has the same dimensions as the object.
3. Laterally Inverted: The image appears reversed from left to right.
4. Equal Distance from the Mirror: The image is formed at the same distance behind the mirror as the object is in front.

Q2. An object is placed at a distance of 12 cm in front of a concave mirror of radius of curvature 30 cm. List four characteristics of the image formed by the mirror. (Delhi 2017)

Ans:

1. Virtual and Erect: The image is formed behind the mirror and is upright.
2. Magnified: The image is larger than the object.
3. Located Behind the Mirror: The image is formed beyond the mirror.
4. Not Real: Since it is virtual, it cannot be obtained on a screen.

Important Questions of Chemical Reaction and Equations

(a) State the law that is followed by balancing a chemical equation.

Ans: The Law of Conservation of Mass states that mass can neither be created nor destroyed. This means that the number of atoms of each element must be equal on both sides of a balanced chemical equation.

(b) Balance the following chemical equation: Na + H3O → NaOH + H2 (Board Exam, 2013)

Which of the following is a correct option? (2020)

(a) (A) and (C)

(b) (C) and (D)

(c) (A), (C) and (D)

(d) (A) and (B)

State the type of chemical reactions, represented by the following equations : (Board Term I, 2014)

(a) A + BC → AC + B

(b) A + B → C

(c) PQ + RS → PS + RQ

(d) A2O3 + 2B → B2O3 + 2A

Ans: Types of Chemical Reactions:

(a) A + BC → AC + B → Displacement reaction

(b) A + B → C → Combination reaction

(c) PQ + RS → PS + RQ → Double displacement reaction

(d) A₂O₃ + 2B → B₂O₃ + 2A → Redox reaction

Q 1. “Only variations that confer an advantage to an individual organism will survive in a population.” Justify this statement. (Foreign 2011)

Ans:

• Variations occur due to genetic changes.
• Beneficial variations help organisms adapt better to their environment, leading to higher survival and reproduction.
• This is the basis of Natural Selection, as per Darwin's theory of evolution.
• Example: A giraffe with a long neck can reach high tree leaves, giving it an advantage over short-necked giraffes.

Q 2. What is a gene? (AI 2014)

Ans: A gene is a segment of DNA that contains the instructions for making proteins. It determines the traits or characteristics inherited by an organism.

Q 3. Write a difference between inherited traits and acquired traits giving one example of each. (Delhi 2013C)

Ans: 

Q 4. (a) Why did Mendel carry out an experiment to study inheritance of two traits in garden pea?

(b) What were his findings with respect to inheritance of traits in F1 and F2 generation?

(c) State the ratio obtained in the F2 generation in the above mentioned experiment. (2020)

Ans: (a) Mendel studied inheritance of two traits to understand whether they are inherited together or separately.

(b) He found that traits are inherited independently and do not affect each other (Law of Independent Assortment).

(c) The F2 generation ratio was 9:3:3:1 for dihybrid crosses.

Important Questions of Carbon and Its Compound

Q 1. Give reasons for the following:

(i) Element carbon forms compounds mainly by covalent bonding.

(ii) Diamond has high melting point.

(iii) Graphite is a good conductor of electricity. (3/5, Foreign 2011)

Ans: (i) Carbon forms compounds by covalent bonding due to its tetravalency, sharing electrons rather than donating or accepting them.

(ii) Diamond has a high melting point because of a strong 3D covalent structure, requiring high energy to break.

(iii) Graphite is a good conductor of electricity due to free-moving delocalized electrons in its layered structure.

Q 2. What are covalent bonds? Show their formation with the help of electron dot structure of methane. Why are covalent compounds generally poor conductors of electricity? (Delhi 2013C)Covalent bond jewelryMolecule model kits

Ans:

• Covalent bonds are formed by the sharing of electrons.

• Electron dot structure:

H | H—C—H | H

Q 3. Name a cyclic unsaturated carbon compound. (2020)

Ans: Benzene (C₆H₆)

Important Questions of Acid, Bases, Salts

Q1. 2 mL of sodium hydroxide solution is added to a few pieces of granulated zinc metal taken in a test tube. When the content are warmed, a gas evolves which is bubbled through a soap solution before testing. Write the equation of the chemical reaction involved and the test to detect the gas. Name the gas which will be evolved when the same metal reacts with dilute solution of a strong acid.

Q 2. To. a solution of sodium hydroxide in a test tube, two drops of phenolphthalein are added.
(i) State the colour change observed.
(ii) If dil HCl is added dropwise to the solution, what will be the colour change?
(iii) On adding few drops of NaOH solution to the above mixture the colour of the solution reappears. Why? (Board Term I, 2013)

Ans: Phenolphthalein Test:

(i) In NaOH solution, phenolphthalein turns pink.

(ii) Adding HCl dropwise, the solution turns colorless.

(iii) Adding NaOH again restores the pink color, as the solution becomes basic.

Q 3. (a) Write the chemical name and formula of marble.
(b) It has been found that marbles of Taj are getting corroded due to development of industrial areas around it. Explain this fact giving a chemical equation.
(c) (i) What happens when CO2 is passed through lime water?
(ii) What happens when CO2 is passed in excess through lime? (Board Term I, 2013)

Important Questions of Periodic Classification

Q1. Why did Mendeleev leave some gaps in the Periodic table?

Ans: 

• He predicted the existence of undiscovered elements and left gaps for them.
• Example: Gallium and Germanium were discovered later and matched his predictions.

Q 2. An element ‘X’ is forming an acidic oxide. Its position in modern periodic table will be

(a) group 1 and period 3

(b) group 2 and period 3

(c) group 13 and period 3

(d) group 16 and period 3. (2020)

Ans: Position of an element forming an acidic oxide:

The correct answer is (d) Group 16 and Period 3, as elements in Group 16 form acidic oxides.

Q 3. List any two properties of the elements belonging to the first group of the Modern Periodic Tablet (AI 2014)

Ans: Two properties of Group 1 elements (Alkali metals):

1. Highly reactive, especially with water.
2. Low melting points and soft texture.

Important Questions of Life Process

Q 1. State the location and function of gastric glands. (Board Term I, 2014)

Ans:

• Location: Inner lining of the stomach.
• Function: Secrete gastric juice (HCl, Pepsin, Mucus) for digestion.

Q 2. (a) State the role played by the following in the process of digestion :

(i) Enzyme trypsin

(ii) Enzyme lipase-

(b) List two functions of finger-like projections present in the small intestine. (2020)

Ans: (i) Trypsin - Breaks proteins into peptides.

(ii) Lipase - Breaks down fats into fatty acids and glycerol.

(b) Functions of finger-like projections (Villi) in the small intestine:

1. Increase surface area for absorption.
2. Help transport absorbed nutrients into the bloodstream.

Q 3. (a) What is peristaltic movement?

Ans: Rhythmic contraction of muscles in the digestive tract to push food forward.
(b) ‘Stomata remain closed in desert plants during daytime’. How do they do photosynthesis? (Board Term I, 2013)

Ans: Stomata remain closed during the day to conserve water and open at night to absorb CO₂, storing it as malic acid for daytime photosynthesis (CAM pathway).

Do Check: Previous Year Question Paper Class 10 Science | CBSE 10th Science Exam Analysis 2025

Watch Live Session on CBSE Class 10 Science Paper Analysis on Our YT 

CBSE Class 10 Science Answer Key 2025 – How It Helps Students

To assist students in evaluating their performance, we have provided the Class 10 Science Board Paper 2025 Answer Key. This key allows students to:

1. Compare their responses with the correct answers.
2. Estimate their probable scores before the official results.
3. Identify strengths and weaknesses for better exam preparation.
4. Understand the correct approach to solving questions effectively.

Do Check: CBSE Class 10 Science Sample Paper 2025

Will CBSE Release the Official Science Answer Key?

The Central Board of Secondary Education (CBSE) is not expected to release the official Answer Key Science Class 10 2025, as the exams are conducted in a single annual session with a subjective format. However, if CBSE decides to publish the official Science answer key, it will be available on the official website (cbse.nic.in). Generally, only objective-type questions have officially released answer keys.

Since CBSE may not release an official key, various coaching institutes and subject experts might publish unofficial Answer Key Class 10 Science 2025. These can help students analyze their performance, accuracy, and time management.

CBSE Class 10 Science Unit-wise Weightage

How to Download the CBSE Class 10 Science Answer Key 2025

Students can download the CBSE Class 10 Science Answer Key 2025 by following these steps:

1. Visit the official CBSE website (cbse.nic.in).
2. Look for the "CBSE Answer Key 2025" section under the latest updates.
3. Click "Class 10 Science Answer Key 2025" and download in PDF Format.
4. Compare your answers with the key to estimate your scores.

Stay tuned for further exam analysis, expert solutions, and question paper PDFs to help you assess your performance in the CBSE Class 10 Science Exam 2025! 

Do Check: CBSE Science Blueprint Class 10 2025

How to Calculate Marks Using CBSE 10th Answer Key 2025?

Students can easily estimate their scores using the CBSE Class 10 Answer Key 2025 by following these simple steps:

Step 1: Download the Answer Key

Visit the official CBSE website (cbse.nic.in) or check reliable educational platforms for the CBSE Class 10 Answer Key 2025 PDF.
Compare your responses with the correct answers provided in the official or expert-released answer key.

Step 2: Assign Marks for Correct Answers

For each correct answer, award yourself the full marks allotted as per the marking scheme.
Ensure that you check section-wise distribution to allocate marks correctly.

Step 3: Calculate Your Expected Score

Add up all the correct answers to determine your total marks.
Verify calculations carefully to get an accurate expected score before the official results.

Step 4: No Negative Marking

The CBSE Class 10 board exams do not have negative marking, so no marks are deducted for incorrect answers. Even if an answer is wrong, your total score remains unaffected.

By using the CBSE Class 10 Answer Key 2025, students can analyze their performance, identify strengths and weaknesses, and estimate their final board exam scores with confidence

Do Check: CBSE Class 10 Science Important Topics | Most Repeated Questions in CBSE Class 10 Science 2025

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