MCQs

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.

Hydrogen is the limiting reactant because 9 moles are required. Six moles of hydrogen produce four moles of ammonia.

Na₂SO₄ contains two sodium ions per formula unit. Therefore, 0.5 mole gives one mole of Na⁺ ions.

Glucose contains six carbon atoms per molecule. Therefore, 0.5 mole of carbon atoms corresponds to 0.5 ÷ 6 = 0.083 mole of glucose.

Each NH₃ molecule contains three hydrogen atoms; therefore one mole of NH₃ contains three moles of hydrogen atoms.

Forty-eight grams of magnesium equal two moles, producing two moles of MgO. The mass becomes 80 g.

One mole occupies 22.4 dm³ at STP, so two moles occupy 44.8 dm³.

One mole of nitrogen produces two moles of nitrogen dioxide. Therefore, 0.5 mole yields one mole.