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ICSE-X-Chemistry

Previous Year Paper year:2019

with Solutions - page 4
 
  • #1-i-iii
    Li, K, Na, H (In the decreasing order of their ionization potential)

    Ans : H > Li > Na > K

    (Smaller the size greater is the ionization potential)
  • #1-i-iv
    F, B, N, O (In the increasing order of electron affinity)

    Ans : B < N < O < F

    (Smaller the size more is the electron affinity)
  • #1-i-v
    Ethane, methane, ethene, ethyne. (In the increasing order of the molecular weight)

    [H = 1, C = 12]

    Ans :
  • #
    Section : II
    [40 Marks]

    (Attempt any four questions from this Section)
  • #2
  • #2-a
    Draw the electron dot structure of :
    [3]
  • #2-a-i
    Nitrogen molecule [N = 7]

    Ans : Nitrogen molecule



    Nitrogen atom shares three electrons forming a triple covalent bond.
  • #2-a-ii
    Sodium chloride [Na = 11, Cl = 17]

    Ans : Sodium chloride



    Sodium loses one electron to chlorine forming a positive ion and chlorine gains one electron forming a negative ion. These ions form an electrovalent bond and are held strongly by electrostatic forces of attraction.
  • #2-a-iii
    Ammonium ion [N = 7, H = 1]

    Ans : Ammonium ion

    N (7) →

    H (1) → Hx

    Formation of ammonia

    Formation of proton

    H - 1e- H+

    Formation of ammonium ion

    Ammonia donates its lone pair to proton forming ammonium ion.
  • #2-b
    The pH values of three solutions A, B and C are given in the table. Answer the following questions:
    [3]


  • #2-b-i
    Which solution will have no effect on litmus solution?
    Ans : C (Because pH 7 is neutral).
  • #2-b-ii
    Which solution will liberate CO2when reacted with sodium carbonate?
    Ans : B (Because acids liberate CO2 gas when treated with carbonates and acids have pH less than 7)
  • #2-b-iii
    Which solution will turn red litmus solution blue?
    Ans : A (Bases turn red litmus blue and they have pH more than 7)
  • #2-c
    Study the extract of the Periodic Table given below and answer the questions that follow. Give the alphabet corresponding to the element in question. DO NOT repeat an element.
    [4]
  • #2-c-i
    Which element forms electrovalent compound with G?
    Ans :
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