9th Class Science Atoms and Molecules Question Bank Atoms and Molecules

  • question_answer
    Match column I with column II and mark the correct option from the codes given below.
    Column I Column II
    (a) 28 g of He (i) 58.5 u
    (b) 0.5 mole of \[{{\text{O}}_{2}}\] (ii) 7 Mol
    (c) Molecular mass of common salt (iii) 60 g
    (d) 1.5 mole of \[\text{Ca}\] (iv) 16 g

    A) (a) - (iv), (b) - (ii), (c) - (iii), (d) - (i)

    B) (a) - (ii), (b) - (iv), (c) - (i), (d) - (iii)

    C) (a) - (ii), (b) - (i), (c) - (iii), (d) - (iv)

    D) (a) - (ii), (b) - (iv), (c) - (iii), (d) - (i)

    Correct Answer: B

    Solution :

    (a) 4 g of He = 1 mole of He \[\therefore \] 28 g of \[\text{He=}\frac{\text{1}}{\text{4}}\text{ }\!\!\times\!\!\text{ 28}\] moles of He =7 moles of He (b) 1 mole of \[{{\text{O}}_{\text{2}}}\text{ = 32 g of }{{\text{O}}_{\text{2}}}\] 0.5 mole of \[{{\text{O}}_{\text{2}}}\text{=32}\times \text{0}\text{.5 g}\]of\[{{\text{O}}_{\text{2}}}=16g\] of \[{{\text{O}}_{\text{2}}}\] (c) Molecular mass of common salt (NaCI) =23 + 35.5 = 58.5 u (d) 1 mole of Ca = 40 g of Ca 1.5 mole of \[\text{Ca = 40}\times \text{1}\text{.5 g}\] of  Ca = 60 g of Ca


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