CBSE Class 10 Science 2023 — Set 1

Questions in this 2023 Science paper (Set 1)

All 39 questions from this set, exactly as asked. Try each one, then open the question-paper PDF above for the complete paper.

1. 1.
   In the experimental setup given below, it is observed that on passing the gas produced in the reaction in the solution 'X', the solution 'X' first turns milky and then colourless. The option that justifies the above stated observation is that 'X' is aqueous calcium hydroxide and (a) it turns milky due to carbon dioxide gas liberated in the reaction and after sometime it becomes colourless due to…
2. 2.
   The emission of brown fumes in the given experimental set-up is due to

   • (a) thermal decomposition of lead nitrate which produces brown fumes of nitrogen dioxide.
   • (b) thermal decomposition of lead nitrate which produces brown fumes of lead oxide.
   • (c) oxidation of lead nitrate forming lead oxide and nitrogen dioxide.
   • (d) oxidation of lead nitrate forming lead oxide and oxygen.
3. 3.
   MnO2 + 4HCl -> MnCl2 + 2H2O + Cl2. In order to balance the above chemical equation, the values of x, y and z respectively are:

   • (a) 6, 2, 2
   • (b) 4, 1, 2
   • (c) 4, 2, 1
   • (d) 2, 2, 1
4. 4.
   The table below has information regarding pH and the nature (acidic/basic) of four different solutions. Which one of the options in the table is correct?

   • (a) Lemon juice | Orange pH paper | pH 3 | Basic
   • (b) Milk of magnesia | Blue pH paper | pH 10 | Basic
   • (c) Gastric juice | Red pH paper | pH 6 | Acidic
   • (d) Pure water | Yellow pH paper | pH 7 | Neutral
   • (a) Lemon juice, Orange pH paper, pH 3…
5. 5.
   A metal 'X' is used in thermite process. When X is burnt in air it gives an amphoteric oxide 'Y'. 'X' and 'Y' are respectively:

   • (a) Fe and Fe2O3
   • (b) Al and Al2O3
   • (c) Fe and Fe3O4
   • (d) Al and Al3O4
6. 6.
   Select washing soda from the following:

   • (a) NaHCO3
   • (b) Na2CO3.5H2O
   • (c) Na2CO3.10H2O
   • (d) NaOH
7. 7.
   Consider the structures of the three cyclic carbon compounds A, B and C given below and select the correct option from the following: (A) is cyclohexane (C6H12, all single bonds) (B) is benzene (C6H6, alternating double bonds) (C) is cyclohexene (C6H10, one double bond)

   • (a) A and C are isomers of hexane and B is benzene.
   • (b) A is an isomer of hexane, B is benzene and C is an isomer of hexene…
8. 8.
   An organism which breaks down the food material outside the body and then absorbs it is

   • (a) a plant parasite, Cuscuta
   • (b) an animal parasite, Tapeworm
   • (c) a bacteria, Rhizobium
   • (d) a fungi, Rhizopus
9. 9.
   Consider the following statements about small intestine and select the one which is NOT correct:

   • (a) The length of the small intestine in animals differs as it depends on the type of food they eat.
   • (b) The small intestine is the site of complete digestion of food.
   • (c) The small intestine receives secretions from liver and pancreas.
   • (d) The villi of the small intestine absorb water from the…
10. 10.
    The statement that correctly describes the characteristic(s) of a gene is:

    • (a) In individuals of a given species, a specific gene is located on a particular chromosome.
    • (b) A gene is not the information source for making proteins in the cell.
    • (c) Each chromosome has only one gene located all along its length.
    • (d) All the inherited traits in human beings are not controlled by genes.
11. 11.
    Select from the following the correct statement about tropic movement in plants:

    • (a) It is due to stimulus of touch and temperature.
    • (b) It does not depend upon the direction of stimulus received.
    • (c) It is observed only in roots and not in stems.
    • (d) It is a growth related movement.
12. 12.
    Select the INCORRECT match (between the plant and its vegetative part) from the following:

    • (a) Bryophyllum, leaf
    • (b) Potato, stem
    • (c) Money-plant, stem
    • (d) Rose, root
13. 13.
    If four identical resistors, of resistance 8 ohm, are first connected in series so as to give an effective resistance Rs, and then connected in parallel so as to give an effective resistance Rp, then the ratio Rs/Rp is

    • (a) 32
    • (b) 2
    • (c) 0.5
    • (d) 16
14. 14.
    In domestic electric circuits the wiring with 15 A current rating is for the electric devices which have

    • (a) higher power ratings such as geyser.
    • (b) lower power ratings such as fan.
    • (c) metallic bodies and low power ratings.
    • (d) non-metallic bodies and low power ratings.
15. 15.
    In the following diagram, the position of the needle is shown on the scale of a voltmeter. The least count of the voltmeter and the reading shown by it respectively are:

    • (a) 0.15 V and 1.6 V
    • (b) 0.05 V and 1.6 V
    • (c) 0.15 V and 1.8 V
    • (d) 0.05 V and 1.8 V
16. 16.
    The resultant magnetic field at point 'P' situated midway between two parallel wires (placed horizontally) each carrying a steady current I is

    • (a) in the same direction as the current in the wires.
    • (b) in the vertically upward direction.
    • (c) zero
    • (d) in the vertically downward direction.
17. 17.
    Assertion (A): The colour of aqueous solution of copper sulphate turns colourless when a piece of lead is added to it. Reason (R): Lead is more reactive than copper, and hence displaces copper from its salt solution.

    • (a) Both (A) and (R) are true and (R) is the correct explanation of (A).
    • (b) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
    • (c) (A) is true, but (R) is…
18. 18.
    Assertion (A): Genes inherited from the parents decide the sex of a child. Reason (R): X chromosome in a male child is inherited from his father.

    • (a) Both (A) and (R) are true and (R) is the correct explanation of (A).
    • (b) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
    • (c) (A) is true, but (R) is false.
    • (d) (A) is false, but (R) is true.
    • (a) Both (A) and (R) are true…
19. 19.
    Assertion (A): Blood clotting prevents excessive loss of blood. Reason (R): Blood clotting is due to blood plasma and white blood cells present in the blood.

    • (a) Both (A) and (R) are true and (R) is the correct explanation of (A).
    • (b) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
    • (c) (A) is true, but (R) is false.
    • (d) (A) is false, but (R) is true.
    • (a) Both (A) and…
20. 20.
    Assertion (A): The strength of the magnetic field produced at the centre of a current carrying circular coil increases on increasing the number of turns in it. Reason (R): The current in each circular turn has the same direction and the magnetic field due to each turn then just adds up.

    • (a) Both (A) and (R) are true and (R) is the correct explanation of (A).
    • (b) Both (A) and (R) are true, but…
21. 21 (a).
    • (i) A compound 'X' which is prepared from gypsum has the property of hardening when mixed with proper quantity of water. Identify 'X' and write its chemical formula.
    • (ii) State the difference in chemical composition between baking soda and baking powder.
22. 22 (a).
    Write the role of insulin in regulating blood sugar levels in human body. Mention the disease caused due to it.
23. 22 (b).
    How is the timing and the amount of release of insulin in the blood regulated?
24. 23 (a).
    Name the type of blood (oxygenated / deoxygenated) transported by each of the following mentioning the path (i.e. from one organ (which place) to another (which place)).

    • (i) Vena cava
    • (ii) Pulmonary artery
25. 24.
    Name the part of the human excretory system where nephrons are found. Write the structure and function of nephrons.
26. 25 (a).
    A narrow beam XY of white light is passing through a glass prism ABC as shown in the diagram. Trace it on your answer sheet and show the path of the emergent beam as observed on the screen PQ. Name the phenomenon observed and state its cause.
27. 26.
    How do harmful chemicals get accumulated progressively at each trophic level in a food chain?
28. 27.
    Identify the oxidising agent in the following reactions:

    • (i) 4NH3 + 5O2 -> 4NO + 6H2O
    • (ii) H2O + F2 -> HF + HOF
    • (iii) Fe2O3 + 3CO -> 2Fe + 3CO2
    • (iv) 2H2 + O2 -> 2H2O
    • (b) Define a redox reaction in terms of gain or loss of oxygen.
29. 28.
    Suggest one remedial measure each to counteract the change in pH in human beings in following cases:

    • (i) Production of too much acid in stomach during indigestion
    • (ii) Sting by a honey bee / nettle leaves
    • (b) Fresh milk has a pH of 6. When it changes into curd will its pH increase or decrease? Why?
30. 29 (a).
    • (i) State the role of ATP in cellular respiration.
    • (ii) What ensures sufficient exchange of gases in plants?
    • (iii) State the conditions on which the direction of diffusion of gases in plant depend upon.
31. 30.
    Complete the following ray diagram to show the formation of image. (Two rays from an object placed between F and 2F of a concave mirror are shown.) (b) Mention the nature, position, and size of the image formed in this case. (c) State the sign of the image distance in this case using the Cartesian sign convention.
32. 31.
    Give reasons for the following:

    • (a) Danger signals installed at airports and at the top of tall buildings are of red colour.
    • (b) The sky appears dark to the passengers flying at very high altitudes.
    • (c) The path of a beam of light passing through a colloidal solution is visible.
33. 32 (a).
    • (i) State the rule used to find the force acting on a current carrying conductor placed in a magnetic field.
    • (ii) Given below are three diagrams showing entry of an electron in a magnetic field. Identify the case in which the force will be (1) maximum and (2) minimum respectively. Give reason for your answer. [Diagram
    • (i) shows electron entering perpendicular to field,
    • (ii) at an angle, (iii)…
34. 33 (a).
    • (i) Why does a kitchen garden called an artificial ecosystem while a forest is considered to be a natural ecosystem?
    • (ii) While designing an artificial ecosystem at home, write any two things to be kept in mind to convert it into a self-sustaining system. Give reason to justify your answer.
35. 34 (a).
    A saturated organic compound 'A' belongs to the homologous series of alcohols. On heating 'A' with concentrated sulphuric acid at 443 K, it forms an unsaturated compound 'B' with molecular mass 28 u. The compound 'B' on addition of one mole of hydrogen in the presence of Nickel, changes to a saturated hydrocarbon 'C'.

    • (i) Identify A, B and C.
    • (ii) Write the chemical equations showing the…
36. 35.
    Name the parts of a bisexual flower that are not directly involved in reproduction. (b) Differentiate between self pollination and cross pollination. List any two significance of pollination. (c) What is the fate of ovules and ovary after fertilization in a flower?
37. 36.
    An electric iron consumes energy at a rate of 880 W when heating is at the maximum rate and 330 W when the heating is at the minimum. If the source voltage is 220 V, calculate the current and resistance in each case. (b) What is heating effect of electric current? (c) Find an expression for the amount of heat produced when a current passes through a resistor for some time.
38. 37.
    Almost all metals combine with oxygen to form metal oxides. Metal oxides are generally basic in nature. But some metal oxides show both basic as well as acidic behaviour. Different metals show different reactivities towards oxygen. Some react vigorously while some do not react at all.

    • (a) What happens when copper is heated in air? (Give the equation of the reaction involved.)
    • (b) Why are some…
39. 38 (a).
    In order to trace the inheritance of traits Mendel crossed pea plants having one contrasting character or a pair of contrasting characters. When he crossed pea plants having round and yellow seeds with pea plants having wrinkled and green seeds, he observed that no plants with wrinkled and green seeds were obtained in the F1 generation. When the F1 generation pea plants were cross-bred by…
40. 39 (a).
    Hold a concave mirror in your hand and direct its reflecting surface towards the sun. Direct the light reflected by the mirror on to a white card-board held close to the mirror. Move the card-board back and forth gradually until you find a bright, sharp spot of light on the board. This spot of light is the image of the sun on the sheet of paper; which is also termed as 'Principal Focus' of the…

Class 10 Science exam pattern (80 marks)

The theory paper carries 80 marks over 3 hours (39 questions, with internal choice in some). Section-wise structure:

Structure per the CBSE 2023-24 sample-paper design; question wording varies by set.

Prepare with

How to use these papers

1. 1Start chapter-wise early in the year — solve only the Science questions from a chapter you have just finished.
2. 2Switch to full timed papers 2–3 months before the exam: one complete set in the real time limit, no notes.
3. 3Self-mark against the marking scheme, then fix every mistake with our free NCERT solutions.
4. 4Re-attempt your weakest chapters until the recurring question types feel routine.

CBSE Class 10 Science 2023 paper — FAQ