1. 1 mole of aluminium oxide (Al₂O₃) = 2 × 27 + 3 × 16 = 102g i.e., 102g of Al₂O₃ = 6.022 × 10²³ molecules of Al₂O₃ Then, 0.051 g of Al₂O₃ contains = 6.022×10²³/102×0.051 molecules = 3.011 × 10²⁰ molecules of Al₂O₃ The number of aluminium ions (Al³⁺) present in one molecules of aluminium oxide is 2. ThRead more

    1 mole of aluminium oxide (Al₂O₃) = 2 × 27 + 3 × 16 = 102g
    i.e., 102g of Al₂O₃ = 6.022 × 10²³ molecules of Al₂O₃
    Then, 0.051 g of Al₂O₃ contains = 6.022×10²³/102×0.051 molecules
    = 3.011 × 10²⁰ molecules of Al₂O₃
    The number of aluminium ions (Al³⁺) present in one molecules of aluminium oxide is 2. Therefore, The number of aluminium ions (Al³⁺) present in
    3.11 × 10²⁰ molecules (0.051g) of aluminium oxide (Al2O3) = 2 × 3.011 × 10²⁰
    = 6.022 × 10²⁰

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  2. 1 mole of solid sulphur (S₈) = 8 × 32g = 256g i.e., 256g of solid sulphur contains = 6.022 × 10²³ molecules Then, 16g of solid sulpur contains 6.022×10²³ /256×16 molecules = 3.76 × 10²² molecules (approx) For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-9/sciencRead more

    1 mole of solid sulphur (S₈) = 8 × 32g = 256g
    i.e., 256g of solid sulphur contains = 6.022 × 10²³ molecules
    Then, 16g of solid sulpur contains 6.022×10²³ /256×16 molecules
    = 3.76 × 10²² molecules (approx)

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  3. (a) 32 g of oxygen gas = 1 mole Then, 12g of oxygen gas = 12/32 mole = 0.375 mole (b) 18g of water = 1 mole Then, 20 g of water = 20/18 mole = 1.11 moles (approx.) (c) 44g of carbon dioxide = 1 mole Then, 22g of carbon dioxide = 22/44 mole = 0.5 mole For more answers visit to website: https://www.tiRead more

    (a) 32 g of oxygen gas = 1 mole
    Then, 12g of oxygen gas = 12/32 mole = 0.375 mole
    (b) 18g of water = 1 mole
    Then, 20 g of water = 20/18 mole = 1.11 moles (approx.)
    (c) 44g of carbon dioxide = 1 mole
    Then, 22g of carbon dioxide = 22/44 mole = 0.5 mole

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  4. (a) The mass of 1 mole of nitrogen atoms is 14g. (b) The mass of 4 moles of aluminium atoms is (4 × 27)g = 108g (c) The mass of 10 moles of sodium sulphite (Na2SO3) is 10 × [2 × 23 + 32 + 3 × 16]g = 10 × 126g = 1260g For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/clRead more

    (a) The mass of 1 mole of nitrogen atoms is 14g.
    (b) The mass of 4 moles of aluminium atoms is (4 × 27)g = 108g
    (c) The mass of 10 moles of sodium sulphite (Na2SO3) is 10 × [2 × 23 + 32 + 3 × 16]g = 10 × 126g = 1260g

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  5. (a) Molar mass of ethyne, C2H2 = 2 × 12 + 2 × 1 = 28g (b) Molar mass of sulphur molecule, S8 = 8 × 32 = 256g (c) Molar mass of phosphorus molecule, P4 = 4 × 31 = 124g (d) Molar mass of hydrochloric acid, HCl = 1 + 35.5 = 36.5g (e) Molar mass of nitric acid, HNO3 = 1 + 14 + 3 × 16 = 63g For more answRead more

    (a) Molar mass of ethyne, C2H2 = 2 × 12 + 2 × 1 = 28g
    (b) Molar mass of sulphur molecule, S8 = 8 × 32 = 256g
    (c) Molar mass of phosphorus molecule, P4 = 4 × 31 = 124g
    (d) Molar mass of hydrochloric acid, HCl = 1 + 35.5 = 36.5g
    (e) Molar mass of nitric acid, HNO3 = 1 + 14 + 3 × 16 = 63g

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-3/

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