CBSE Class 10 Science 2025
366 questions · 761 marks · 355 with the board’s own marking-scheme answer, 11 with no official answer on the site.
Marks by chapter
Counted from the 366 questions listed below, as the 2025 papers print them. CBSE allocates marks per unit, not per chapter — this is what was observed, not an official CBSE weightage. Every year compared →
| Chapter | Marks | Share |
|---|---|---|
| Life Processes41 questions | 76 | 10.0% |
| Electricity35 questions | 73 | 9.6% |
| Light - Reflection and Refraction31 questions | 69 | 9.1% |
| Carbon and its Compounds21 questions | 69 | 9.1% |
| Metals and Non-metals35 questions | 68 | 8.9% |
| How do Organisms Reproduce?27 questions | 63 | 8.3% |
| Magnetic Effects of Electric Current23 questions | 60 | 7.9% |
| Control and Coordination25 questions | 54 | 7.1% |
| Acids, Bases and Salts28 questions | 49 | 6.4% |
| Chemical Reactions and Equations28 questions | 48 | 6.3% |
| Heredity22 questions | 47 | 6.2% |
| The Human Eye and the Colourful World25 questions | 46 | 6.0% |
| Our Environment24 questions | 38 | 5.0% |
| Periodic Classification of Elements1 question | 1 | 0.1% |
366 questions from 2025
- Q1Example of thermal decomposition reaction are (i) 2 AgCl → 2 Ag+Cl_2 (ii) CaCO_3 → CaO+CO_2 (iii) 2 H_2 O → 2 H_2+O_2…1 mk
- Q1In the following experimental setup of electrolysis of water, if P and Q are the gases collected in the test tubes…1 mk
- Q1The main observations while performing the experiment of burning magnesium ribbon in air are: (i) Magnesium ribbon…1 mk
- Q1In the electrolysis of water, the mass ratio of hydrogen and oxygen gases liberated at the electrodes is:1 mk
- Q1In which one of the following situations a chemical reaction does not occur?1 mk
- Q1Electrolysis of water is a decomposition reaction. The mass ratio (M_H: M_O) of hydrogen and oxygen gases liberated at…1 mk
- Q1Consider the following chemical equation: pAl+q H_2 O → rAl_2 O_3+s H_2 To balance this chemical equation, the values…1 mk
- Q1The correct balanced chemical equation showing exothermic reaction in which natural gas burns in air is:1 mk
- Q2A metal, M, displaces iron from aqueous solution of ferrous sulphate but fails to do so in case of aqueous solution of…1 mk
- Q2Which of the given option represents a family of salts?1 mk
- Q2In order to prepare dry hydrogen chloride gas in humid atmosphere the gas produced is passed through a guard tube…1 mk
- Q2The products formed when Aluminium and Magnesium are burnt in the presence of air respectively are:1 mk
- Q2The formula of washing soda is1 mk
- Q2You have three aqueous solutions A, B and C as given below: A - Potassium nitrate B - Ammonium chloride C - Sodium…1 mk
- Q2The warning sign shown in the given figure must invariably be displayed/pasted on the containers which contain…1 mk
- Q3An element 'M' has 25\% of the electrons filled in the third shell as in the second shell. The element ' M ' is:1 mk
- Q3A few pieces of granulated zinc are taken in a test tube and 2 mL of sodium hydroxide solution is added to it. When the…1 mk
- Q3Which one of the following metals is protected from corrosion by a layer of its own oxide?1 mk
- Q3The property by virtue of which a solid material can be drawn into thin wires is called:1 mk
- Q3Select from the following a statement which is not true about burning of magnesium ribbon in air:1 mk
- Q3In one formula unit of salt 'X', seven molecules of water of crystallisation are present. The salt 'X' is:1 mk
- Q3The 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…1 mk
- Q3The chlorine produced during the electrolysis of brine solution is used in the manufacture of:1 mk
- Q3The most common method of extraction of metals from their oxide ores is:1 mk
- Q3A common feature observed in the crystals of washing soda, copper sulphate, gypsum and ferrous sulphate is that all1 mk
- Q3The body of human beings works within the pH range of:1 mk
- Q4Consider the following reactions: (i) Dilute hydrochloric acid reacts with sodium hydroxide. (ii) Magnesium oxide…1 mk
- Q4Select from the following a hydrocarbon having one C-C bond and one C ≡ C bond:1 mk
- Q4Given below are the structures of some hydrocarbons. Select the two structures which are related to each other from the…1 mk
- Q4A metal, 'X', on treatment with sodium hydroxide liberates a gas 'G'. It also liberates the same gas, 'G' on treatment…1 mk
- Q4Study the following cases: (i) CuSO_4+Mg → (ii) FeSO_4+Pb → (iii) CaSO_4+Al → (iv) ZnSO_4+Ca → The case/cases in which…1 mk
- Q4Aluminium powder is used in thermit welding because:1 mk
- Q4A Hydrocarbon which does not belong to the same homologous series of carbon compounds is1 mk
- Q5Two metals zinc and tin are dissolved separately in definite proportions in molten copper (the primary metal) to obtain…1 mk
- Q5The colour of the solution observed after about 1 hour of placing iron nails in copper sulphate solution is1 mk
- Q5When a mixture of baking soda and tartaric acid is heated (or mixed in water) a product 'X' is formed, which is…1 mk
- Q5Reaction between two elements A and B, forms a compound C. A loses electrons and B gains electrons. Which one of the…1 mk
- Q5Tooth enamel is made up of calcium hydroxyapatite (a crystalline form of calcium phosphate). This chemical starts…1 mk
- Q5Choose the incorrect statement about the common reaction used in hydrogenation of vegetable oils.1 mk
- Q5The values of a, b, c and d in the following balanced chemical equation are respectively: a Pb(NO_3)_2 → heat b PbO+c…1 mk
- Q5The essential element taken up from the soil by the plants to synthesize proteins is:1 mk
- Q6During electrolytic refining of copper, the anode, the cathode and the electrolyte used respectively are1 mk
- Q6Select TRUE statements about lymph from the following: A. Lymph vessels carry lymph through the body and finally open…1 mk
- Q6Juice of tamarind turns blue litmus to red. It is because of the presence of a chemical compound called1 mk
- Q6Match Column-I with Column-II and select the correct option from the choices provided.1 mk
- Q6The essential element used in the synthesis of proteins is:1 mk
- Q6The metals obtained from their molten chlorides by the process of electrolytic reduction are:1 mk
- Q6Select the correct option from the following statements about the functioning of the human heart.1 mk
- Q6The opening and closing of stomata is regulated by:1 mk
- Q6The nature of aqueous solution of potassium nitrate is:1 mk
- Q7The part of the brain which maintains the posture and balance of the body is:1 mk
- Q7One-cell thick blood vessels are known as:1 mk
- Q7The part of the hind-brain controlling involuntary actions such as salivation and vomiting in humans is:1 mk
- Q7The formation of magnesium oxide is correctly shown in option:1 mk
- Q7Plants like rose and banana have lost the capacity to produce:1 mk
- Q7The water of crystallization is present in (i) Bleaching Powder (ii) Plaster of Paris (iii) Washing Soda (iv) Baking…1 mk
- Q7If we make carbon skeleton with four carbon atoms, the two different possible skeletons will be1 mk
- Q7The growth of the pollen tubes towards ovules is an example of:1 mk
- Q8Secretion of less saliva in mouth will effect the conversion of:1 mk
- Q8Listed below are the steps of nutrition in Amoeba. Select the correct sequence of these steps: (i) Diffusion of simple…1 mk
- Q8A tall pea plant with round seeds (TTRR) is crossed with a short pea plant with wrinkled seeds (ttrr). The F_1…1 mk
- Q8Mendel obtained F_2 generation by1 mk
- Q8The plant hormone present in greater concentration in the areas of rapidly dividing cells is:1 mk
- Q8Which one of the following has half the number of chromosomes and half the amount of DNA as compared to the…1 mk
- Q8Electrical impulse travels in a neuron from1 mk
- Q8Observe the given figures A and B. When chhui-mui (sensitive) plant is touched, its leaves fold. This is due to: Figure…1 mk
- Q8In a bisexual flower the male gametes are present in the:1 mk
- Q9The plant hormone whose concentration stimulates the cells to grow longer on the side of the shoot which is away from…1 mk
- Q9Select a pair of bisexual flowers from the following:1 mk
- Q9Which among the following is not a neural action controlled by the part of human brain labelled 'X' in the figure above?1 mk
- Q9Which one of the following statements is not correct for the plants raised by vegetative propagation?1 mk
- Q9Bryophyllum produces new plant through:1 mk
- Q9A pair of endocrine glands located in the human brain is1 mk
- Q9Which of the following is the correct sequence of parts of female reproductive system of flowering plants in terms of…1 mk
- Q9When a pure-tall pea plant is crossed with a pure-dwarf pea plant, the percentage of tall pea plants in F_1 and F_2…1 mk
- Q10Parasitic mode of nutrition is observed in:1 mk
- Q10Select the option having correct matching of the organism given in Column I with the mode of reproduction in Column II:1 mk
- Q10To get an image of magnification -1 on a screen using a lens of focal length 20 cm, the object distance must be:1 mk
- Q10When a seed germinates the root grows downwards and a small shoot grows upward. This shoot is known as1 mk
- Q10Temporary finger-like extensions on the cell surface to take in food is formed in:1 mk
- Q10The correct/true statement(s) for a bisexual flower is/are: (i) They possess both stamen and pistil. (ii) They possess…1 mk
- Q10The gastric glands present in the wall of the stomach release:1 mk
- Q10The modes of reproduction in Spirogyra and Planaria respectively are1 mk
- Q10The number of chromosomes in a cell division is halved. This kind of cell division is observed in:1 mk
- Q11If the absolute refractive indices of two media X and Y are 6/5 and 4/3 respectively, then the refractive index of Y…1 mk
- Q11Which one of the following is not an excretory product in plants?1 mk
- Q11A candle flame is placed in front of the reflecting surface of a convex mirror of focal length f. If the distance of…1 mk
- Q11The plant hormones promoting rapid cell division in seeds and wilting of leaves respectively are1 mk
- Q11An optical device 'X' is placed obliquely in the path of a narrow parallel beam of light. If the emergent beam gets…1 mk
- Q11Absolute refractive index of water and glass is 4/3 and 3/2 respectively. If the speed of light in glass is 2 × 10^8 m…1 mk
- Q11The basic filtration unit of the excretory system in human beings is:1 mk
- Q11If pea plants with round and green seeds (RRyy) are crossed with pea plants having wrinkled and yellow seeds (rrYY),…1 mk
- Q12In human alimentary canal, the digestive juice secreted by the gastric glands are1 mk
- Q12A piece of wire of resistance 'R' is cut lengthwise into three identical parts. These parts are then connected in…1 mk
- Q12An object is placed at a distance of 30 cm from the pole of a concave mirror. If its real and inverted image is formed…1 mk
- Q12Select the correct statement from the following:1 mk
- Q12In aerobic respiration, the steps are: breakdown of glucose to pyruvate and its further conversion to carbon dioxide.…1 mk
- Q12When a beam of white light passes through a region of very fine dust particles, the colour of light that scatters the…1 mk
- Q12The breakdown of glucose has taken the following pathway: Glucose →(a) Pyruvate + Energy →(b) Lactic acid + Energy The…1 mk
- Q13The curvature of eye lens of human eye1 mk
- Q13In the human eye, most of the refraction for the light rays entering the eye occurs at the surface of:1 mk
- Q13The part of the human eye which can modify the curvature of the eye lens to some extent is:1 mk
- Q13In order to obtain large images of the teeth of patients, the dentist holds the concave mirror in such a manner that…1 mk
- Q13Identify from the following the ray diagram which shows the correct path of the reflected ray for the ray incident on a…1 mk
- Q13Mirror 'X' is used to concentrate sunlight in solar furnace and Mirror 'Y' is fitted on the side of the vehicle to see…1 mk
- Q13The white light entering a glass prism, gets split into its constituent colours. It is observed that:1 mk
- Q13A wire of length ' l ' is gradually stretched so that its length increases to 3 l. If its original resistance is R,…1 mk
- Q13In the given figure the angle of incidence and the angle of deviation respectively are:1 mk
- Q13An electric bulb is rated 220 V; 11 W. The resistance of its filament when it glows with a power supply of 220 V is:1 mk
- Q13In domestic electric circuits, the colour of insulation covers of wires in the cables of electric iron/electric toaster…1 mk
- Q14The possible way to restore clear vision of those people whose eyeball has elongated is the use of suitable1 mk
- Q14The minimum number of identical bulbs of rating 4V; 6W, that can work safely with desired brightness, when connected in…1 mk
- Q14Most of the refraction for the light rays entering the eye occurs at1 mk
- Q14Which one of the following statements is not true about a bar magnet?1 mk
- Q14The part of human eye which controls the amount of light entering into it.1 mk
- Q14An old person is suffering from an eye defect caused by weakening of ciliary muscles and diminishing flexibility of the…1 mk
- Q14The resistivity of a wire made of an alloy is generally:1 mk
- Q14An electric bulb is connected to a power supply of 220 V. If the current drawn by the bulb from the supply is 500 mA,…1 mk
- Q14A boy while reading a book, keeps it much beyond 25 cm from his eyes. This defect of vision has arised because of1 mk
- Q15Four identical resistors of 12 Ω each are connected in series to form a square ABCD as shown in the figure. The…1 mk
- Q15The examples of natural and manmade (artificial) ecosystems are respectively1 mk
- Q15Consider the following ray diagram: Here, the angle of incidence and angle of deviation respectively are1 mk
- Q15Which of the following groups do not constitute a food chain? (i) Wolf, rabbit, grass, lion (ii) Plankton, man,…1 mk
- Q15The phenomenon responsible for making the smoke particles visible when a beam of sunlight enters a smoke filled room…1 mk
- Q15In the following groups of wastes, which group contains only non- biodegradable wastes?1 mk
- Q15Consider the following food chain: Grass → Grasshopper → Frog → Snake → Eagle If the amount of energy available at…1 mk
- Q15In the food chains given below. Select the most efficient food chain in terms of energy:1 mk
- Q15The strength of magnetic field produced inside a long straight current carrying solenoid does not depend upon:1 mk
- Q15The strength of the magnetic field produced inside a current carrying long straight solenoid does not depend upon:1 mk
- Q16Other than the abiotic components, which of the given biotic components are not required to make an aquarium with small…1 mk
- Q16Which one of the following gets biomagnified at different levels in a food chain?1 mk
- Q16Identify from the following a group containing all non-biodegradable substances.1 mk
- Q16The incorrect statement about ozone is1 mk
- Q16Green plants occupy the first trophic level in every food chain because they1 mk
- Q16Human activities that are affecting the environment are:1 mk
- Q16The percentage of solar energy which is not converted into food energy by the leaves of green plants in a terrestrial…1 mk
- Q17Assertion: Propanal and propanone are structural isomers. Reason (R): Propanal and propanone both have the same…1 mk
- Q17Assertion: Carbon and its compounds are our major sources of fuels. Reason (R): Most of the carbon compounds on burning…1 mk
- Q17Assertion: All exothermic reactions are accompanied with evolution of heat and light. Reason (R): Combination reactions…1 mk
- Q17Assertion: Ductility is that property of metals which enables copper to be used in making cooking utensils. Reason (R):…1 mk
- Q17Assertion: Silver chloride turns grey in sunlight. Reason (R): Decomposition of silver chloride into silver and…1 mk
- Q17Assertion: In large animals, oxygen can reach different parts of the animal's body easily. Reason (R): Respiratory…1 mk
- Q17Assertion: Decomposition reactions are generally endothermic reactions. Reason (R): Decomposition of organic matter…1 mk
- Q17Assertion (A): The metals high up in the reactivity series cannot be obtained from their compounds by heating with…1 mk
- Q17Assertion: Brass is prepared by first melting copper and then dissolving tin into it in a definite proportion. Reason…1 mk
- Q17Assertion: Hydrogen gas is not evolved when a metal reacts with nitric acid. Reason (R): Nitric acid is a strong…1 mk
- Q18Assertion: Concentrated nitric acid is diluted by adding water slowly to acid with constant stirring. Reason (R):…1 mk
- Q18Assertion: In our actions of writing or talking, our nervous system communicates with the muscles. Reason (R): Cranial…1 mk
- Q18Assertion: A mango seed will germinate to form a mango tree. Reason (R): Heredity determines the process by which…1 mk
- Q18Assertion: Xylem tissue moves water and minerals obtained from the soil by the roots. Reason (R): Xylem tissue is found…1 mk
- Q18Assertion: A human child bears all the basic features of human beings. Reason (R): It looks exactly like its parents,…1 mk
- Q18Assertion: The embryo gets nutrition from the mother's blood with the help of a special tissue called placenta. Reason…1 mk
- Q19Assertion: The bending of a wire in the form of a coil of several turns does not affect its electrical resistance.…1 mk
- Q19Assertion: In reptiles, the temperature at which the fertilized eggs are kept decides the sex of the offsprings. Reason…1 mk
- Q19Assertion: The pattern of the magnetic field of a solenoid carrying a current is similar to that of a bar magnet.…1 mk
- Q19Assertion: Nichrome is an alloy which is commonly used in electrical heating devices such as electric irons, toasters,…1 mk
- Q19Assertion (A): Magnetic field lines around a bar magnet never intersect each other. Reason (R): Magnetic field produced…1 mk
- Q19Assertion: In the common domestic circuits the earth wire is connected to a metallic plate buried deep inside the…1 mk
- Q19Assertion: No two magnetic field lines are found to cross each other. Reason (R): The compass needle cannot point…1 mk
- Q20Assertion: The amount of ozone in the atmosphere began to drop sharply in the 1980s. Reason (R): The oxygen atoms…1 mk
- Q20Assertion: When ciliary muscles contract, eye lens becomes thin. Reason (R): Ciliary muscles control the power of the…1 mk
- Q20Assertion (A): Use of jute bags for shopping reduces pollution. Reason (R): Jute is biodegradable and its bag may be…1 mk
- Q20Assertion (A): Animals will not get energy if they eat (consume) coal as food. Reason (R): Specific enzymes are needed…1 mk
- Q20Assertion: Food web is a network of several food chains operating in an ecosystem. Reason (R): Food web decreases the…1 mk
- Q20Assertion: White light is dispersed by a glass prism into seven colours. Reason (R): The red light bends the least…1 mk
- Q20Assertion: All organisms can make organic compounds like sugar and starch from inorganic substances using radiant…1 mk
- Q21Cinnabar is an ore of a metal 'X'. When this ore is heated in air, it is first converted into oxide of 'X' (XO) and…2 mk
- Q21While burning a magnesium ribbon in air, list two safety measures which should be followed. Also state two observations…2 mk
- Q21Name the compound used in black and white photography. State whether the reaction that occurs is exothermic or…2 mk
- Q21A light green coloured solution of sulphate salt of metal 'P' is taken in a beaker, a rod of another metal "Q" is put…2 mk
- Q21Balance the following chemical equations: CO_2+H_2 O →[ Chlorophyll ] Sunlight C_6 H_12 O_6+O_2+H_2 O Pb(NO_3)_2 → Heat…2 mk
- Q21A student performs the following experiment in his school laboratory. List two observations to justify that in this…2 mk
- Q21Define oxidation. Identify and name the substance oxidised in the following reaction: CuO+H_2 → Cu+H_2 O2 mk
- Q21A crystalline substance of green colour 'X' emits gases of characteristic odour when heated over a flame. It first…2 mk
- Q21List the possible sources of energy required in decomposition reactions. Illustrate any one with a suitable example. OR…2 mk
- Q21An object is placed at a distance of 10 cm in front of a concave mirror of focal length 15 cm. Use mirror formula to…2 mk
- Q21Name a metal found in the earth's crust (i) in free state and (ii) in the form of its compound. State where each of…2 mk
- Q21During an experiment, a student observes that the given mirror is forming an erect and diminished image for all…2 mk
- Q21In common practice silver is recovered from silver nitrate solution by the use of copper metal. Name the type of…2 mk
- Q21A gas 'X' is found in the upper layer of atmosphere. It is a deadly poison, but still essential for all life forms on…2 mk
- Q22Consider two lamps A and B of rating 50 W; 220 V and 25 W; 220 V respectively. Find the ratio of the resistances of the…2 mk
- Q22How is brain protected in our body? A doctor finds in one of his patients that he is not maintaining a proper posture…2 mk
- Q22What are micelles? Draw the structure.2 mk
- Q22Determine the maximum and minimum resistance which can be obtained by joining five resistors of 1/5 Ω each. OR…2 mk
- Q22Show the formation of calcium chloride by the transfer of electrons from one element to the other. Atomic Number of…2 mk
- Q22Write the formula of the ions which (i) acids, and (ii) bases generate in water solutions. Dry HCl gas does not change…2 mk
- Q22A chemical compound 'X' is used to bleach washed clothes in laundry as well as to make drinking water free from germs.…2 mk
- Q22Use Ohm's law to determine the potential difference across the 6 Ω resistor in the following circuit when key is…2 mk
- Q22Draw labelled diagrams to show different stages of budding in Hydra.2 mk
- Q22Show the formation of magnesium chloride by electron transfer. Write the name of the cation and anion present in the…2 mk
- Q22Consider the following circuits: (iii) In which circuit will the power dissipated in the circuit be (I) minimum (II)…2 mk
- Q22Giving reason, state the advantage of using baking powder over baking soda for the preparation of bread or cakes.2 mk
- Q22Give reasons: The male reproductive organ responsible for formation of germ cells is located outside the abdominal…2 mk
- Q22Select from the following the members of same homologous series: (1) (2) (3) (4) What happens to (i) the melting point,…2 mk
- Q23State the main function of veins in human circulatory system. Why do they not need thick walls?2 mk
- Q23Name the tissues which form the vascular bundle. State their function in plants.2 mk
- Q23When an incident ray of light enters a medium 'X' from air, it bends towards the normal. Infer about the following with…2 mk
- Q23How is lymph formed? State its important function. OR Identify 'X' in the figure of human nephron shown below. What…2 mk
- Q23Besides minimising the loss of blood, why is it essential to plug any leak in a blood vessel? Name the component of…2 mk
- Q23An object is placed at a distance of 30 cm in front of a concave mirror of focal length 20 cm. Use mirror formula to…2 mk
- Q23Name the parts of hind-brain of the human brain. Which part of the hind-brain controls involuntary actions such as…2 mk
- Q23"Proteins control the expression of various characters." Explain this statement by taking an example of "tallness" as a…2 mk
- Q23A person is making a list to purchase few things from a nearby market. Explain how the fore-brain plays an important…2 mk
- Q23"In human alimentary canal the small intestine is designed to absorb the digested food." Justify this statement.2 mk
- Q23Study the given diagram and write the type of movement exhibited by: Root, and Shoot, mentioning the stimulus in each…2 mk
- Q23"Plants use a variety of techniques to get rid of waste material." Justify this statement giving any four ways.2 mk
- Q23State the main function of arteries. Why do they have thick and elastic walls?2 mk
- Q24Explain how the proteins control the 'characteristics' in an organism with the help of an example of 'short height'…2 mk
- Q24An object is placed at a distance of 60 cm from a concave lens of focal length 30 cm. Use lens formula to find the…2 mk
- Q24Study the figure in which the path of a ray of light going from Medium 1 to Medium 2 is shown. Out of the two Media -…2 mk
- Q24Write one function each of the following, in a seed: (i) Seed coat (ii) Cotyledon (iii) Radicle (iv) Plumule OR Write…2 mk
- Q24Explain with the help of a flow chart that in human beings father is responsible for the sex (male or female) of the…2 mk
- Q24The values of absolute refractive indices of kerosene and water are 1.44 and 1.33 respectively. Compare the two media…2 mk
- Q24"Sex of the children is determined by type of sex chromosome which they inherit from their father." Justify the…2 mk
- Q24Pure-tall (TT) pea plants are crossed with pure-dwarf (tt) pea plants. The pea plants obtained in F_1 generation are…2 mk
- Q24Explain how the proteins control the 'characteristics' in an organism with the help of an example of 'tallness' trait…2 mk
- Q25Give reasons: (i) The sky appears dark to passengers flying at very high altitude. (ii) 'Danger' signal lights are red…2 mk
- Q25A wire of resistance R is cut into three equal parts. If these three parts are then joined in parallel, calculate the…2 mk
- Q25Out of the two lenses, one concave and the other convex, state which one will diverge a parallel beam of light falling…2 mk
- Q25Study the food web given below: Identify the food chain(s) in which the eagle receives the highest energy from the…2 mk
- Q25A student has difficulty in reading his textbooks but can read the blackboard clearly while sitting in the last row.…2 mk
- Q25Draw a ray diagram to show the refraction of a ray of light passing through an equilateral glass prism. Mark the angle…2 mk
- Q25State two applications of Joule's heating in domestic electric circuit. Establish the relationship between the…2 mk
- Q26Why are the organisms of first trophic level important in any food chain? Justify the following statement: 'The flow of…2 mk
- Q26"Excessive use of chemicals and pesticides in agriculture adversely effect the environment." Justify this statement.2 mk
- Q26State the role of an electric fuse, used in series with an electrical appliance. Why should in an electric circuit a…2 mk
- Q26A copper wire on burning in flame, gets coated with a black substance. Write the chemical equation of the reaction that…2 mk
- Q26Write the percentage of the energy of sunlight captured by green plants, to convert it into food energy. Explain the…2 mk
- Q26What happens when: (write balanced chemical equation) Lead nitrate is thermally decomposed, Natural gas burns in oxygen…2 mk
- Q26How and why is an electric fuse used in an electric circuit? Briefly describe its function.2 mk
- Q26Draw the pattern of magnetic field lines due to a current carrying straight conductor. Mark on it the direction of…2 mk
- Q26Four resistors, each of resistance 2 · 0 Ω, are joined end to end to form a square ABCD as shown. Using appropriate…2 mk
- Q26Translate the following statements into chemical equations and then balance them: Nitric acid reacts with calcium…2 mk
- Q26An electric kettle is rated 750 W; 220 V. Can this kettle be used in a circuit which has a fuse of current rating 3 A?…2 mk
- Q26Indicate the flow of energy in a food chain operating in an ecosystem. Why is it uni-directional? Give reason.2 mk
- Q26What are magnetic field lines. List two important properties of magnetic field lines.2 mk
- Q26We do not clean natural ponds or lakes whereas an aquarium or a swimming pool needs to be cleaned regularly. Why?2 mk
- Q26Write chemical equation for the chemical reaction between the aqueous solutions of sodium sulphate and barium chloride.…2 mk
- Q26A voltage source sends a current of 2 A to a resistor of 40 Ω connected across it for 5 minutes. Calculate the…2 mk
- Q26An electric kettle is rated 230 V; 1000 W. Calculate the resistance of its heating element when in operation.2 mk
- Q26An electric fuse is rated 8 A. Can it be used with an electrical appliance of rating 5 kW, 200 V? Justify your answer.2 mk
- Q27Why do we balance a chemical equation? Name and state the law that suggests the balancing of a chemical equation?…3 mk
- Q27State the change that is observed when a China dish containing copper powder is heated over the flame of a burner. Name…3 mk
- Q27Write balanced chemical equation for the reactions that occur when steam is passed over red hot iron. natural gas is…3 mk
- Q27"Displacement reactions also play a key role in extracting metals in the middle of the reactivity series." Justify this…3 mk
- Q27How is a double displacement reaction different from a displacement reaction? Explain giving example in the form of…3 mk
- Q27Define one ampere. The resistance of a wire of 0.01 cm radius is 14 Ω. If the resistivity of the material of the wire…3 mk
- Q27What is short circuiting? State its possible causes. What is likely to happen if a domestic circuit gets short…3 mk
- Q27Write chemical formula of washing soda. How is it obtained from baking soda? List two uses of washing soda.3 mk
- Q27Answer the following questions for a case in which a current carrying conductor is placed in a uniform magnetic field:…3 mk
- Q27Explain why respiration is considered as an exothermic reaction. Give the chemical equation for this reaction.3 mk
- Q27Define one volt potential difference between two points in an electric field. Draw a schematic diagram of an electric…3 mk
- Q27What is a reactivity series of elements? How is it developed? Arrange the following elements as they are arranged in…3 mk
- Q27(i) Define the term decomposition reaction. Write one chemical equation each for decomposition reaction where energy is…3 mk
- Q28Two substances 'A' and 'B' are burnt in air separately. For 'A', ashes are collected and dissolved in water to get…3 mk
- Q28Study the experimental set-up given in the figure and answer the following questions: Identify these metals from the…3 mk
- Q28Name and describe the most widely used method for refining impure metals?3 mk
- Q28In an experiment a student dipped pH papers in four different solutions A, B, C and D and reported his observation as…3 mk
- Q28Design an activity to show that metals are good conductors of heat and have high melting points.3 mk
- Q28Common salt is an important raw material for various chemicals of daily use. State in brief the method of preparation…3 mk
- Q28Samples of four metals A, B, C and D were added one by one to the following solutions. The results obtained were…3 mk
- Q28With the help of an activity, explain the conditions under which iron articles get rusted. OR (i) Name two metals which…3 mk
- Q28Write the electron-dot structures of (i) sodium, and (ii) oxygen. Using these structures, show the formation of sodium…3 mk
- Q28Observe the following diagram showing an experiment to determine the conditions under which a metal ' M ' corrodes.…3 mk
- Q28State the chemical property in each case on which the following uses of baking soda are based upon: (i) as an…3 mk
- Q29An object of size 5 cm is placed at a distance of 30 cm from the optical centre of a converging lens of focal length 20…3 mk
- Q29Name the blood vessel that brings (i) oxygenated blood (ii) deoxygenated blood, to the human heart. Also name that…3 mk
- Q29The digestion of food in human alimentary canal is a complex process. State the enzyme/salt present in the following…3 mk
- Q29What is meant by reflex arc? Where are they formed in the human body? Why have reflex arcs evolved in animals?3 mk
- Q29(i) Study the diagram and name the parts marked as A, B, C and D. (ii) Write the function of A and C.3 mk
- Q29Define hormone. "Hormones should be secreted in precise quantities. We have a feedback mechanism through which this is…3 mk
- Q29Write the name and one function of respiratory pigment found in human beings. Why do lungs always contain a residual…3 mk
- Q29Plants have neither a nervous system nor muscles, even then they respond to stimuli. For example, the leaves of…3 mk
- Q29What is the first step of cellular respiration? In which part of the cell does it occur? Write the equation for the…3 mk
- Q29Why is blood circulation in vertebrates known as "double circulation"? Trace its path in the form of a flow chart.3 mk
- Q29On the basis of the characteristics of the processes given in the brackets in each case, differentiate between the…3 mk
- Q29Enlist any two nitrogenous waste products removed from the blood of human kidney. Name the capillary cluster formed by…3 mk
- Q30Differentiate between self-pollination and cross pollination. Which one of the two is better for the survival of…3 mk
- Q30"In human beings the genes inherited from the parents decide whether the newborn individual is male or female." Explain…3 mk
- Q30Define fertilisation. What happens to Zygote, Ovule, Ovary and Stamens after fertilisation in a flowering plant?3 mk
- Q30A pure pea plant bearing terminal flowers was cross-pollinated with a pure plant having axillary flowers. In F_1…3 mk
- Q30The lowest part of the ear called earlobe, is closely attached to the side of the head in some of us (Figure 'X'), and…3 mk
- Q30A pure pea plant having round (R), yellow (Y) seeds is crossed with another pure pea plant having wrinkled (r), green…3 mk
- Q30How many chromosomes are present in human beings? Out of these how many are sex chromosomes? Explain how, in sexually…3 mk
- Q30What are chromosomes? Explain in brief how stability of DNA content of a species is ensured in sexually reproducing…3 mk
- Q30State two limitations of electrical impulses in multicellular organisms. Why is chemical communication better than…3 mk
- Q30The gene combination of purple flowered pea plants is denoted as (WW) and that of white flowered pea plants as (ww),…3 mk
- Q31Draw ray diagrams to show the nature, position and relative size of the image formed by a convex mirror when the object…3 mk
- Q31If we want to obtain a real and magnified image of an object by using a concave mirror of focal length 18 cm. Where…3 mk
- Q31A person is suffering from an eye defect in which the far point of the eye is much nearer than infinity. Name the…3 mk
- Q31If we want to obtain a virtual and magnified image of an object by using a concave mirror of focal length 18 cm, where…3 mk
- Q31The power of a lens is -0.25 D. Based on this information, find out The type of lens and its focal length. The eye…3 mk
- Q31A convex lens forms an 8.0 cm long image of a 2.0 cm long object which is kept at a distance of 6.0 cm from the optical…3 mk
- Q31An object is placed at a distance of 20 cm from the optical centre of a concave lens and its image is formed on the…3 mk
- Q31List three raw materials required by terrestrial plants for photosynthesis. Explain how nature provides these raw…3 mk
- Q31What is a rainbow? Draw a labelled diagram to show its formation.3 mk
- Q31A hormone 'X' is secreted in blood when a person is under scary situation. Identify the hormone 'X' and the gland that…3 mk
- Q31A convex mirror used for rear view on an automobile has a focal length of 1.5 m. If a 3 m high bus is located at 6.0 m…3 mk
- Q31A person has to keep reading material much beyond 25 cm (say at 50 cm) from the eye for comfortable reading. Name the…3 mk
- Q31A student placed a candle flame at different distances from a convex lens and focused its image on a screen. He…3 mk
- Q32The resistance of a wire of 0.01 cm radius is 7 ohms. If the resistivity of the material of the wire is 44 × 10^-6 ohm…3 mk
- Q32The electrical resistivity of three materials A, B and C at 20°C is given below: (i) Classify these materials as…3 mk
- Q32Consider the following electric circuit: Calculate the values of the following: The total resistance of the circuit The…3 mk
- Q32Resistance of a wire of length 1 m is 35 Ω at 20°C. If the diameter of the wire is 0.2 mm, determine the resistivity of…3 mk
- Q32Draw a labelled diagram to show the pattern of magnetic field lines on a horizontal white board due to a straight…3 mk
- Q32Differentiate between a gamete and a zygote. State their significance in sexual reproduction.3 mk
- Q32Define the term "potential difference" between two points in an electric circuit carrying current. Name and define its…3 mk
- Q32In one of Mendalian experiments, when F_1 generation pea plants with round yellow seeds were self-pollinated, pea seeds…3 mk
- Q32Name and state the rule which determines the force on a current carrying conductor placed in a uniform magnetic field.…3 mk
- Q32Consider a rectangular cardboard having two holes P and Q through which a current carrying circular loop has been…3 mk
- Q32A person uses lenses of +2.0 D power in his spectacles for the correction of his vision. Name the defect of vision the…3 mk
- Q32Three resistors of 2 Ω, 3 Ω and 6 Ω are connected in (i) series, and (ii) parallel. Draw the arrangements of the…3 mk
- Q33Write the relationship between resistivity and resistance of a cylindrical conductor of length l and area of…3 mk
- Q33Draw a diagram to show the dispersion of white light by a glass prism. What is spectrum? Give reason for its formation.3 mk
- Q33Explain the statement "Potential difference between two points is 1 volt". What do the symbols given below represent in…3 mk
- Q33Name the glands that secrete: (i) Adrenaline (ii) Thyroxin Explain with example how the timing and amount of hormone…3 mk
- Q33Give reasons for the following: Rate of breathing in aquatic animals is much faster than terrestrial organisms. Rings…3 mk
- Q33"The third wire of earth connection is very important in domestic electric appliances." Justify this statement. List…3 mk
- Q33Some harmful chemicals get accumulated in human bodies through the food chain. Name this phenomenon. Explain the reason…3 mk
- Q33Write the essential function performed by ozone at the higher levels of the atmosphere. How is it formed in the upper…3 mk
- Q33"In a food chain energy flow is unidirectional." Give two reasons for the given statement. If 10,000 J energy is…3 mk
- Q33What are decomposers? Give two examples. State how they maintain a balance in an ecosystem.3 mk
- Q34(i) What are structural isomers? Draw structural isomers of butane (C_4 H_10). Give reason why propane has no…5 mk
- Q34A carbon compound 'A' on heating with excess conc. H_2 SO_4 forms a compound 'B', which on addition of one mole of…5 mk
- Q34(i) Consider the following metals: K, Ca, Al, Cu, Ag, Fe Select from the above metals, a metal which I. does not react…5 mk
- Q34What is meant by the term homologous series of carbon compounds? Write molecular formula of any two consecutive members…5 mk
- Q34Define the term "Functional group of a carbon compound". Write the formula of functional group present in (i) propanol…5 mk
- Q34(i) Draw two isomeric structures of Butene (C_4 H_8). (ii) Name the following compounds: (iii) Write the chemical…5 mk
- Q34Name an alcohol and a carboxylic acid having two carbon atoms in their structures. Draw their structures and state how…5 mk
- Q34(i) A compound 'X' having two carbon atoms in its molecule turns blue litmus red and 5-8 % solution of 'X' in water is…5 mk
- Q35A saturated organic compound 'A' with two carbon atoms belongs to the homologous series of alcohols. On oxidation, it…5 mk
- Q35(i) "The length of the small intestine in various animals depends on the food they eat." Justify the statement. (ii)…5 mk
- Q35(i) What is regeneration? Give one example of an organism that shows this process and one organism that does not. Why…5 mk
- Q35Define the term "homologous series of carbon compounds". Write a homologous series of compounds having functional group…5 mk
- Q35Analyse the given situations and interpret the possible reason for each: (i) Iodine deficiency in diet increases the…5 mk
- Q35(i) Write the functions of the following parts of human female reproductive system: (I) Ovary (II) Fallopian tube (III)…5 mk
- Q35(i) Identify the parts 'X' and 'Y' in the figure given below: (ii) Name the yellowish coloured structures produced by…5 mk
- Q35Define Puberty. List any two changes seen in boys at the time of puberty. Why are testes in human males located outside…5 mk
- Q35Name the parts marked as 'A' and 'B' in the given diagram. Write in detail the changes that take place in a flower when…5 mk
- Q35Name the method by which Amoeba and Leishmania reproduce. Write a major difference in the way they divide to produce…5 mk
- Q36(i) "In refraction of light through a rectangular glass slab, the emergent ray is always parallel to the direction of…5 mk
- Q36The given figure shows the current passing through the straight conductor XY. (i) Copy the diagram and draw the…5 mk
- Q36(i) Draw electron dot structure of chlorine molecule. ( Atomic Number of Chlorine =17) (ii) What happens when chlorine…5 mk
- Q36(i) Draw the pattern of the magnetic field lines for the two parallel straight conductors carrying current of same…5 mk
- Q36Study the following electric circuit diagram and answer the questions that follow: (i) What does the circuit diagram…5 mk
- Q36Observe the following diagram and compare (i) speed of light and (ii) optical densities of the three media A, B and C.…5 mk
- Q36What are magnetic field lines? How is the direction of magnetic field at a point determined? Draw the pattern of…5 mk
- Q36(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…5 mk
- Q37Acid-base indicators can be used to distinguish between an acid and a base. Universal indicator, a mixture of several…4 mk
- Q37Seawater contains many salts dissolved in it. Common salt is separated from these salts. Deposits of solid salt are…4 mk
- Q37The combining capacity of various elements depends on the number of valence electrons. Also the reactivity of elements…4 mk
- Q37Many pure metals like copper, iron and gold are very soft and as such are considered unsuitable for certain uses.…4 mk
- Q37Common salt is a very important chemical compound for our daily life. It's chemical name is sodium chloride and it is…4 mk
- Q37'A' and 'B' are two salts used for washing purposes. Salt 'A' is used for bathing also. Four test tubes I, II, III and…4 mk
- Q38In human beings, there are 23 pairs of chromosomes. Out of these 23 pairs of chromosomes (i.e. 46 chromosomes), 22…4 mk
- Q38A person while climbing up a rocky hill comes into a panic state and fear. His body starts reacting in a…4 mk
- Q38The growth movements of plant parts in which the direction of the stimulus determines the direction of the response is…4 mk
- Q38The maintenance functions of all living organisms must go on even when they are not doing anything particular. Even…4 mk
- Q38In life there are certain changes in the environment called 'stimuli' to which we respond appropriately. Touching a…4 mk
- Q38When a girl is born, the ovaries already contain thousands of immature eggs. On reaching puberty, some of these start…4 mk
- Q39A person allowed a narrow beam of white light from the sun to enter a dark room through a small aperture and placed a…4 mk
- Q39In order to obtain magnetic field lines around a bar magnet, a student performed an experiment using a magnetic compass…4 mk
- Q39Study the circuit shown in which two resistors X and Y of resistances 3 Ω and 6 Ω respectively are joined in series…4 mk
- Q39In our homes, we receive the supply of electric power through a main supply also called mains, either supported through…4 mk
- Q39As shown in the diagram, an electric circuit consisting of an ammeter, a voltmeter, 4 cells of 1 · 5 V each, a plug key…4 mk
- Q39The students in a class took a thick sheet of cardboard and made a small hole in its centre. Sunlight was allowed to…4 mk
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