MCQs

Gas volumes follow mole ratios. Ratio N₂:H₂ = 1:3. Therefore 5 dm³ nitrogen requires 15 dm³ hydrogen.

Molecular formula is C₆H₁₂O₆ because 180/30 = 6. Thus each mole contains 12 moles hydrogen atoms.

Twelve moles of water react with one mole Al₄C₃. Mass = 12 × 18 = 216 g.

16 g CH₄ = 1 mol. One mole methane requires two moles oxygen. Mass = 2 × 32 = 64 g.

Benzene contains six carbon atoms in each molecule, so one mole contains six moles of carbon atoms.

The balanced equation shows equal coefficients for K and KOH, giving a simplified ratio of 1:1.

10 g CaCO₃ = 0.1 mol. One mole CaCO₃ gives one mole CO₂. Therefore volume = 0.1 × 22.4 = 2.24 dm³.

Urea contains two nitrogen atoms per molecule. Thus 0.5 mol nitrogen atoms correspond to 0.25 mol urea. Mass = 0.25 × 60 = 15 g.

From the ratio, 2 mol H₂S produce 3 mol S. Therefore, 1 mol H₂S produces 1.5 mol S. Mass = 1.5 × 32 = 48 g.

One mole of CCl₄ contains 4 moles of Cl atoms. Thus 0.5 mol contains 2 mol Cl atoms.

Atomic mass = mass of one atom × Avogadro's number = 2.66 × 10⁻²³ × 6.022 × 10²³ ≈ 16 u.

4.6 g Na = 0.2 mol. From the equation, 2 mol Na produce 1 mol H₂. Hence 0.2 mol Na produces 0.1 mol H₂.

One formula unit produces 5 ions (2 Al³⁺ + 3 SO₄²⁻). Therefore, 0.1 mol gives 0.5 mol ions = 3.011 × 10²³ ions.

Moles of CS₂ = 19/76 = 0.25 mol. According to the equation, 1 mol CS₂ produces 2 mol SO₂. Therefore, 0.25 mol CS₂ forms 0.5 mol SO₂. Mass = 0.5 × 64 = 32 g.

Twenty-five grams equal 0.25 mole CaCO₃. The same amount of CO₂ occupies 5.6 dm³ at STP.

1.6 g oxygen equals 0.05 mole. Therefore, the number of molecules equals 0.05 × Avogadro's number.

One mole Pb(NO₃)₂ forms one mole PbO whose molar mass is 223 g.

Each mole KMnO₄ contains four moles oxygen atoms. Therefore, 0.25 mole contains one mole oxygen atoms.

Iron provides only 0.5 mole while sulfur provides 0.625 mole. Iron is present in the smaller stoichiometric amount.