Practice Questions

22 g CO₂ = 0.5 mole. One mole of CO₂ contains one mole of carbon atoms. Mass of carbon = 0.5 × 12 = 6 g.

1.7 g NH₃ = 0.1 mole. Each NH₃ molecule has 10 electrons. Therefore, total electrons = 0.1 × 10 × Nₐ = 6.022 × 10²³.

Mole ratio S:H₂S = 3:2. Moles of S = 0.5 × 3/2 = 0.75 mole. Mass = 0.75 × 32 = 24 g.

Moles of O₂ = 16 ÷ 32 = 0.5 mole. By Avogadro's law, equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. Therefore, the same volume of CO₂ also contains 0.5 mole.

0.5 × 6 = 3 moles of oxygen atoms. Therefore, the oxygen subscript is 6.

2 moles C₂H₆ require 7 moles O₂. Mass = 7 × 32 = 224 g.

32.5 g Zn = 0.5 mole. It gives 0.5 mole H₂. Volume = 0.5 × 22.4 = 11.2 dm³.

143.5 g = 0.5 mole washing soda. Water = 0.5 × 10 = 5 moles.

Fe:H₂ = 3:4. For 3 moles H₂, Fe = 2.25 moles. Mass = 2.25 × 56 = 126 g.

Molar mass = Density × 22.4 = 1.964 × 22.4 ≈ 44 g/mol.