MCQs

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.

3.011 × 10²³ molecules = 0.5 mole. Volume = 0.5 × 22.4 = 11.2 dm³.

108 g Al = 4 moles. The ratio 4Al : 2Al₂O₃ gives 2 moles Al₂O₃.

50 g CaCO₃ = 0.5 mole. It forms 0.5 mole CaO. Mass = 0.5 × 56 = 28 g.

44.8 dm³ = 2 moles NH₃. Each molecule has 4 atoms. Total atoms = 8 moles of atoms = 4.8176 × 10²⁴ atoms.

30 g of C₂H₆ = 1 mole. One mole of C₂H₆ produces 3 moles of H₂O. Mass of water = 3 × 18 = 54 g.

Molar mass = (4.4 × 10⁻²² g) × (6.022 × 10²³ mol⁻¹) ≈ 265 g/mol.

The volume ratio SO₂ : SO₃ is 1:1. Hence, 44.8 dm³ of SO₂ produces 44.8 dm³ of SO₃.

Each AlCl₃ gives 4 ions. Therefore, 0.5 × 4 = 2 moles of ions. Number of ions = 2 × 6.022 × 10²³ = 1.2044 × 10²⁴.

Moles = 1 ÷ 22.4 = 0.0446 mol. Molar mass = 1.25 ÷ 0.0446 ≈ 28 g/mol.

Moles of N₂ = 28 ÷ 28 = 1 mole. One mole of N₂ forms 2 moles of NH₃. Volume = 2 × 22.4 = 44.8 dm³.

The mole ratio Na : NaCl is 1:1. Therefore, 0.5 moles of Na produce 0.5 moles of NaCl. Mass = 0.5 × 58.5 = 29.25 g.

Moles of CO₂ = 88 ÷ 44 = 2.0 moles. Molecules = 2.0 × 6.022 × 10²³ = 1.2044 × 10²⁴.

Moles of O₂ = 64 g ÷ 32 g/mol = 2.0 moles. At STP, molar volume is 22.4 dm³. Therefore, volume = 2.0 × 22.4 = 44.8 dm³.