CBSE Class 10 Science 2025 Question Paper

Electrolysis of water is a decomposition reaction. The mass ratio $(M_H : M_O)$ of hydrogen and oxygen gases liberated at the electrodes during electrolysis of water is :

The products formed when Aluminium and Magnesium are burnt in the presence of air respectively are :

The following table shows the pH values of four solutions A, B, C and D on a pH scale. The solutions A, B, C and D respectively are of a

Consider the following reactions : (i) Dilute hydrochloric acid reacts with sodium hydroxide. (ii) Magnesium oxide reacts with dilute hydrochloric acid. (iii) Carbon dioxide reacts with sodium hydroxide. It is found that in each case :

Reaction between two elements A and B, forms a compound C. A loses electrons and B gains electrons. Which one of the following properties will not be shown by compound C ?

The metals obtained from their molten chlorides by the process of electrolytic reduction are :

The formation of magnesium oxide is correctly shown in option :

Secretion of less saliva in mouth will effect the conversion of :

The plant hormone whose concentration stimulates the cells to grow longer on the side of the shoot which is away from light is :

The correct/true statement(s) for a bisexual flower is/are : (i) They possess both stamen and pistil. (ii) They possess either stamen or pistil. (iii) They exhibit either self-pollination or cross-pollination. (iv) They cannot produce fruits on their own.

If pea plants with round and green seeds (RRyy) are crossed with pea plants having wrinkled and yellow seeds (rrYY), the seeds developed by the plants of $F_1$ generation will be :

The breakdown of glucose has taken the following pathway : Glucose $\xrightarrow{(a)} Pyruvate + Energy \xrightarrow{(b)} Lactic\ acid + Energy$ The sites 'a' and 'b' respectively are :

Mirror 'X' is used to concentrate sunlight in solar furnace and Mirror 'Y' is fitted on the side of the vehicle to see the traffic behind the driver. Which of the following statements are true for the two mirrors ? (i) The image formed by mirror 'X' is real, diminished and at its focus. (ii) The image formed by mirror 'Y' is virtual, diminished and erect. (iii) The image formed by mirror 'X' is virtual, diminished and erect. (iv) The image formed by mirror 'Y' is real, diminished and at its focus.

An old person is suffering from an eye defect caused by weakening of ciliary muscles and diminishing flexibility of the eye lens. If the defect of vision is 'a' which can be corrected by lens 'b', then 'a' and 'b' respectively are :

Which of the following groups do not constitute a food chain ? (i) Wolf, rabbit, grass, lion (ii) Plankton, man, grasshopper, fish (iii) Hawk, grass, snake, grasshopper, frog (iv) Grass, snake, wolf, tiger

The percentage of solar energy which is not converted into food energy by the leaves of green plants in a terrestrial ecosystem is about :

Assertion (A) : Decomposition reactions are generally endothermic reactions. Reason (R) : Decomposition of organic matter into compost is an exothermic process.

Assertion (A) : A human child bears all the basic features of human beings. Reason (R) : It looks exactly like its parents, showing very little variations.

Assertion (A) : No two magnetic field lines are found to cross each other. Reason (R) : The compass needle cannot point towards two directions at the point of intersection of two magnetic field lines.

Assertion (A) : The amount of ozone in the atmosphere began to drop sharply in the 1980s. Reason (R) : The oxygen atoms combine with molecular oxygen to form ozone.

A student performs the following experiment in his school laboratory. List two observations to justify that in this experiment a chemical change has taken place.

Draw labelled diagrams to show different stages of budding in Hydra.

(a) Besides minimising the loss of blood, why is it essential to plug any leak in a blood vessel? Name the component of blood which helps in this process and state how this component perform this function. OR (b) (i) The transport system in plants is relatively slower than in animals. Give reasons. (ii) State the role of phloem in the transport of materials in plants.

An object is placed at a distance of $60\ cm$ from a concave lens of focal length $30\ cm$. Use lens formula to find the position of the image formed in this case.

(a) A wire of resistance R is cut into three equal parts. If these three parts are then joined in parallel, calculate the total resistance of the combination so formed. OR (b) Define electric power. When do we say that the power consumed in an electric circuit is 1 watt?

"Excessive use of chemicals and pesticides in agriculture adversely effect the environment." Justify this statement.

(a) "Displacement reactions also play a key role in extracting metals in the middle of the reactivity series." Justify this statement with two examples. (b) Why can metals high up in the reactivity series not be obtained by reduction of their oxides by carbon?

(a) With the help of an activity, explain the conditions under which iron articles get rusted. OR (b) (i) Name two metals which react violently with cold water. List any three observations which a student notes when these metal are dropped in a beaker containing water. (ii) Write a test to identify the gas evolved (if any) during the reaction of these metals with water.

Plants have neither a nervous system nor muscles, even then they respond to stimuli. For example, the leaves of chhui-mui (touch-me-not) plant when touched begin to fold up and droop. (a) How is the information communicated in "touch-me-not" plants? (b) What enables the plant cells to bring out the observable response? (c) Differentiate the movement mentioned above from the movement of tendrils in a pea plant.

(a) What are chromosomes? (b) Explain in brief how stability of DNA content of a species is ensured in sexually reproducing organisms?

Draw ray diagrams to show the nature, position and relative size of the image formed by a convex mirror when the object is placed (i) at infinity and (ii) between infinity and pole P of the mirror.

Consider the following electric circuit : Calculate the values of the following : (a) The total resistance of the circuit (b) The total current drawn from the source (c) Potential difference across the parallel combination of $10\ \Omega$ and $15\ \Omega$ resistors

(a) Write the relationship between resistivity and resistance of a cylindrical conductor of length $l$ and area of cross-section A. Hence derive the SI unit of resistivity. (b) Why are alloys used in electrical heating devices?

(a) (i) Draw two isomeric structures of Butene $(C_4H_8)$. (ii) Name the following compounds (structural formulas of chloropropane isomers given). (iii) Write the chemical equations for the following reactions. Mention one essential condition each for these reactions to take place. (I) Ethanol undergoes complete oxidation (II) Propene undergoes hydrogenation (III) Ethanoic acid reacts with ethanol OR (b) (i) A carbon compound X is a good solvent. On reaction with sodium, X forms two products Y and Z. Z is used to convert vegetable oil into vegetable ghee. Identify and name X, Y and Z. Also write the equation of reaction of X with sodium to justify your answer. (ii) Write chemical equation to show what happens when ethanol : (I) burns in oxygen/air. (II) is heated at $443\ K$ in excess conc. $H_2SO_4$. (III) reacts with acidified potassium dichromate.

(a) (i) Write the functions of the following parts of human female reproductive system : (I) Ovary (II) Fallopian tube (III) Uterus (ii) State briefly two contraceptive methods used by human males. OR (b) (i) Differentiate between self-pollination and cross-pollination. (ii) Identify A, B and C in the diagram given below and write one function of each.

(a) (i) The power of a lens 'X' is $-2.5\ D$. Name the lens and determine its focal length in cm. For which eye defect of vision will an optician prescribe this type of lens as a corrective lens? (ii) "The value of magnification 'm' for a lens is $-2$." Using new Cartesian Sign Convention and considering that an object is placed at a distance of $20\ cm$ from the optical centre of this lens, state : (I) the nature of the image formed; (II) size of the image compared to the size of the object; (III) position of the image, and (IV) sign of the height of the image. (iii) The numerical values of the focal lengths of two lenses A and B are $10\ cm$ and $20\ cm$ respectively. Which one of the two will show higher degree of convergence/divergence? Give reason to justify your answer. OR (b) (i) Draw a ray diagram to show the refraction of a ray of light through a rectangular glass slab when it falls obliquely from air into glass. (ii) State Snell's law of refraction of light. (iii) Differentiate between the virtual images formed by a convex lens and a concave lens on the basis of : (I) object distance, and (II) magnification.

Seawater contains many salts dissolved in it. Common salt is separated from these salts. Deposits of solid salt are also found in several parts of the world. These large crystals are often brown due to impurities. This is called rock salt and is mined like coal. The common salt is an important raw material for chemicals of daily use. (a) Write balanced chemical equations to show the products formed during electrolysis of brine. [1] (b) List two uses of any one product obtained during electrolysis of brine. [1] (c) (i) A mild non-corrosive basic salt 'A', used for faster cooking, is strongly heated to produce a compound 'B', that is used for removing permanent hardness of water. Identify A and B and also write the equation for the reaction that occurs when A is heated. [2] OR (c) (ii) Define water of crystallisation. Give two examples of salts that have water of crystallisation. [2]

The maintenance functions of all living organisms must go on even when they are not doing anything particular. Even when we are just sitting in a class or even asleep, this maintenance job has to go on. These maintenance processes require energy to prevent damage and break-down of cells and tissues, which is obtained by the individual organism from the food prepared by the autotrophs, called producers. (a) Name and define the process by which green plants prepare food. [1] (b) Write chemical equation involved in the above process. [1] (c) (i) State in proper sequence the events that occur in synthesis of food by desert plants. [2] OR (c) (ii) Explain giving reasons what happens to the rate at which the green plants will prepare food (I) during cloudy weather, and (II) when stomata get blocked due to dust. [2]

In our homes, we receive the supply of electric power through a main supply also called mains, either supported through overhead electric poles or by underground cables. In our country the potential difference between the two wires (live wire and neutral wire) of this supply is $220\ V$. (a) Write the colours of the insulation covers of the line wires through which supply comes to our homes. [1] (b) What should be the current rating of the electric circuit ($220\ V$) so that an electric iron of $1\ kW$ power rating can be operated? [1] (c) (i) What is the function of the earth wire? State the advantage of the earth wire in domestic electric appliances such as electric iron. [2] OR (c) (ii) List two precautions to be taken to avoid electrical accidents. State how these precautions prevent possible damage to the circuit/appliance. [2]