Percent composition

What is the percent by mass of magnesium in MgO?

• 20%
• 40%
• 50%
• 60%

What is the percent composition by mass of sulfur in the compound MgSO₄ (gram formula mass = 120 g/mol)?

• 20%
• 27%
• 46%
• 53%

What is the percent by mass of calcium in CaF₂ (gram-formula mass = 78 g/mol)?

• 24%
• 49%
• 51%
• 65%

In which compound is the percent composition by mass of Cl equal to 42%?

• HClO (gram formula mass = 52 g/mol)
• HClO₂ (gram formula mass = 68 g/mol)
• HClO₃ (gram formula mass = 84 g/mol)
• HClO₄ (gram formula mass = 100 g/mol)

What is the percent by mass of fluorine in CaF₂ (gram-formula mass = 78 g/mol)?

• 24%
• 49%
• 51%
• 65%

What percent of Zn₃(PO₄)₂ is zinc?

• 33.15%
• 16.04%
• 50.81%
• 19.68%

What is the molar mass of CO₂?

• 44.01 g/mol
• 56.02 g/mol
• 58.93 g/mol
• 117.06 g/mol

Which one is empirical?

• H₂O₂
• C₂H₆O₁₂
• CaCl₂
• N₂O₈

What is the mass of 2.50 mol of oxygen gas O₂?

• 40 g
• 80 g
• 16 g
• 32 g

Which compound has the smallest molar mass?

• CO
• CO₂
• H₂O
• H₂O₂