Q47 of 203 Page 174

What mass of nitrogen, N2, will contain the same number of molecules as 1.8 g of water, H2O? (Atomic masses: N = 14 u; H = 1 u; O = 16 u)

Given mass of water = 1.8g

Molar mass of water = 18g


No. of moles of water = given mass of the element/ molar mass of the element = 1.8g/18g = 0.1 moles


Equal number of moles of all the substances contain equal number of molecules.


So, 0.1 moles of water and 0.1 moles of nitrogen contains same no. of molecules.


Hence, mass of 0.1 mole of nitrogen = 0.1 × 28 g = 2.8 g.


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45

Which contains more molecules, 10 g of sulphur dioxide (SO2) or 10 g of oxygen (O2)?


(Atomic masses: S = 32 u; O = 16 u)

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What weight of oxygen gas will contain the same number of molecules as 56 g of nitrogen gas? (O = 16 u; N = 14 u)

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If one gram of sulphur contains x atoms, calculate the number of atoms in one gram of oxygen element. (Atomic masses: S = 32 u; O = 16 u)

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How many grams of magnesium will have the same number of atoms as 6 grams of carbon? (Mg = 24 u; C = 12 u)