Percent Composition Quiz

What is the percent by mass of oxygen in MgO?

• 20%
• 40%
• 50%
• 60%

What is the percent by mass of magnesium in MgO?

• 20%
• 40%
• 50%
• 60%

What is the percent by mass of sodium in NaCl?

• 39%
• 61%
• 35%
• 65%

Tags

NGSS.HS-PS1-7

What is the percent by mass of chlorine in NaCl?

• 39%
• 61%
• 35%
• 65%

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

• 24%
• 49%
• 51%
• 65%

Tags

NGSS.MS-PS1-1

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

• 20%
• 27%
• 46%
• 53%

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)

Which of the following is NOT needed to calculate percent composition?

• Mass of specific element
• Molar Mass
• Avogadro's Number
• Division

What is the molar mass of PbSO₄

• 303.3 g/mol
• 294.7g/mol
• 163.8g/mol
• 372g/mol

Use the given the chemical equation to answer the following question:

2C₂H₆ + O₂ → 4CO₂ + 6H₂O

What does the number 4 represent for the formula unit 4CO2 ?

• The number 4 represents the coefficient, which is also equal to the number of grams of the formula unit above.

• The number 4 represents the subscript, which is also equal to the number of moles of the formula unit above.

• The number 4 represents the coefficient, which is also equal to the number of moles of the formula unit above.

• The number 4 represents the subscript, which is also equal to the number of grams of the formula unit above.