MCQs

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%.

Number of moles is inversely proportional to molar mass.

The atomic mass of helium is four grams per mole.

The ratio of H₂O to CO₂ is 3:2. Therefore, 3 moles of CO₂ correspond to 4.5 moles of H₂O.

OH⁻ contains eight electrons from oxygen, one from hydrogen, and one extra electron due to the negative charge.

One mole of phosphorus molecules requires five moles of oxygen. Therefore, 0.25 mole requires 1.25 moles.

One methane molecule contains ten protons. Thus, one mole contains 10 × Avogadro's number of protons.

Actual yield equals 80% of theoretical yield. Therefore, 0.80 × 5 = 4 moles.

One atomic mass unit is defined as one-twelfth the mass of a carbon-12 atom.

Sixty-four grams of SO₂ equal one mole, producing one mole of SO₃.

The molar mass divided by Avogadro's number gives the mass of one molecule.

Half a mole of CO₂ occupies 11.2 dm³ at STP.

The sample contains 0.25 mole of CO₂. Since one mole weighs 44 g, the mass is 11 g.