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ICSE Class 10 Chemistry Question 12 of 18

Solved 2020 Question Paper ICSE Class 10 Chemistry — Question 12

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12
Question

Question 5(c)

(i) State the volume occupied by 40 gm of methane at STP, if its vapour density (V.D.) is 8.

(ii) Calculate the number of moles present in 160 gm of NaOH.

[Atomic Mass: Na = 23, H= 1, O= 16]

Answer

(i) Gram molecular mass of methane = V.D. x 2 = 8 x 2 = 16 g

16 g of methane occupies 22.4 lit.

∴ 40 g of methane will occupy = 22.416\dfrac{22.4}{16} x 40 = 56 lits.

(ii) Gram molecular mass of NaOH = 23 + 16 + 1 = 40 g

40 g of NaOH = 1 mole

∴ 160 g of NaOH = 16040\dfrac{160}{40} = 4 moles.