MCQs

Multiplication by Avogadro's number gives approximately 56 g mol⁻¹, the atomic mass of iron.

One mole pentane forms eleven moles of gaseous products. One-quarter mole forms 2.75 moles.

Gas volumes follow mole ratios. Hydrogen volume is three times nitrogen volume.

Molecular formula becomes C₆H₁₂O₆, containing twelve hydrogen atoms.

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

One mole methane requires two moles oxygen. Therefore, oxygen required is 64 g.

Benzene contains six carbon atoms per molecule.

Equal coefficients indicate equal numbers of moles.

Ten grams correspond to 0.1 mole CaCO₃, producing 0.1 mole CO₂ occupying 2.24 dm³ at STP.

The sample contains 0.25 mole urea. With molar mass 60 g mol⁻¹, the mass equals 15 g.

One mole H₂S produces 1.5 moles sulfur. The mass becomes 1.5 × 32 = 48 g.

Every molecule contains four chlorine atoms. Therefore, 0.5 mole CCl₄ contains 2 moles of chlorine atoms.

Multiplying the mass of one atom by Avogadro's number gives approximately 16 g mol⁻¹.

4.6 g Na equals 0.2 mole. According to the equation, 2 moles Na produce 1 mole H₂. Thus, 0.2 mole Na produces 0.1 mole H₂.

One formula unit produces five ions. Therefore, 0.1 mole gives 0.5 mole of ions, equal to 3.011 × 10²³ ions.

Nineteen grams correspond to 0.25 mole CS₂. This produces 0.5 mole SO₂ having a mass of 32 g.

Avogadro's law relates gas volume directly with the number of molecules at constant temperature and pressure.

The balanced equation is 3Fe + 4H₂O → Fe₃O₄ + 4H₂. Their sum is 12.

Percentage yield = (0.45 ÷ 0.75) × 100 = 60%.