PYQ Vault

Day 234: CBSE Class 10 Science

5 questions (8 parts). Try each one first, then open its answer.

  1. Question 1

    Electricity. Asked once: 2025

    32
    The electrical resistivity of three materials A, B and C at 20°C is given below :
    MaterialResistivity (Ω\Omega m)
    A101710^{17}
    B44×10−644 \times 10^{-6}
    C1.62×10−81.62 \times 10^{-8}
    (i) Classify these materials as conductor, alloy and insulator. (ii) Give one example of each of these materials and state one use of each material in the design of an electrical appliance say an electric stove or an electric iron.

  2. Question 2

    Acids, Bases and Salts. Asked once: 2024

    28
    (i) The pH of a sample of tomato juice is 4.6. How is this juice likely to be in taste ? Give reason to justify your answer. (ii) How do we differentiate between a strong acid and a weak base in terms of ion-formation in aqueous solutions ? (iii) The acid rain can make the survival of aquatic animals difficult. How ?

  3. Question 3

    Control and Coordination. Asked once: 2023

    35 (a)
    (i) List three points of difference between nervous and hormonal mechanisms for control and coordination in animals. (ii) How are auxins related with the bending of plant shoot towards unidirectional light ? Explain.

  4. Question 4 (case study, 4 parts)

    Electricity. Asked once: 2024

    When electric current flows in a purely resistive circuit electrical energy gets fully converted into heat energy. The amount of heat produced (H) in the circuit is found to be directly proportional to (i) the square of current (I2)(I^2) (ii) the resistance (R) of the conductor and (iii) the time (t) for which current flows. In other words H=I2RtH = I^2Rt. Electrical devices such an electric fuse, electric heater, electric iron etc. are all based on this effect called heating effect of electric current.
    39 (a)
    List two properties of heating elements.
    39 (b)
    List two properties of electric fuse.
    39 (c)
    Name the principle on which an electric fuse works. Explain how a fuse wire is capable of saving electrical appliances from getting damaged due to accidently produced high currents.
    39 (c) OR
    The power of an electric heater is 1100 W. If the potential difference between the two terminals of the heater is 220 V, find the current flowing in the circuit. What will happen to an electric fuse of rating 5 A connected in this circuit ?

  5. Question 5

    Acids, Bases and Salts. Asked once: 2024

    3
    The salt present in tooth enamel is :

    Tap an option to check your answer.