PYQ Vault

Day 139: CBSE Class 10 Science

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

  1. Question 1

    Metals and Non-metals. Asked once: 2025 (same type asked 2 times)

    22 (A)
    Show the formation of magnesium chloride by electron transfer. Write the name of the cation and anion present in the compound formed. (Atomic Number of Mg = 12, Cl = 17)

  2. Question 2 (case study, 4 parts)

    Metals and Non-metals. Asked once: 2025 (same type asked 2 times)

    Many pure metals like copper, iron and gold are very soft and as such are considered unsuitable for certain uses. Metallic objects around us such as cooking utensils, statues, ornaments, guns etc. are actually not made up of pure metals. Instead of pure metals, alloys are used in the design of most of the useful objects. Making alloys enhances the basic properties of a metal which is the primary constituent (metal) of an alloy.
    37 (I)
    How does electrical conductivity and melting point of a metal change when it is converted to its alloy by mixing a small amount of an element in it ?
    37 (II)
    Name an alloy used for welding two wires together in an electric circuit. Write its major constituents.
    37 (III) (a)
    What are alloys ? How is ‘Brass’ (an alloy) prepared ?
    37 (III) (b)
    What is stainless steel ? How is it prepared ? Write one important property which makes it more useful in making cooking utensils as compared to its primary metal.

  3. Question 3

    Our Environment. Asked once: 2022 (same type asked 2 times)

    13
    (a) Name the group of organisms which form in the first trophic level of all food chains. Why are they called so ? (b) Why are the human beings most adversely affected by bio-magnification ? (c) State one ill-effect of the absence of decomposers from a natural ecosystem.

  4. Question 4

    Acids, Bases and Salts. Asked once: 2025 (same type asked 2 times)

    3
    In one formula unit of salt ‘X’, seven molecules of water of crystallisation are present. The salt ‘X’ is :

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  5. Question 5

    Carbon and its Compounds. Asked once: 2025 (same type asked 2 times)

    34 (a)
    (i) A compound ‘X’ having two carbon atoms in its molecule turns blue litmus red and 5 – 8% solution of ‘X’ in water is widely used as a preservative. Identify the compound ‘X’ and write its structure. (ii) Compare its pH nature with a mineral acid. (iii) ‘X’ on reacting with alcohols produces sweet smelling compounds, used in making perfumes. Name the reaction and write its chemical equation. (iv) When sodium carbonate is added to ‘X’, a colourless gas is produced which turns lime water milky. Write the chemical equation for the reaction giving the name of the salt produced.