Empirical Formula and Molecular Formula and Percent Composition

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%

What is the percent by mass of chlorine in NaCl?

• 39%
• 61%
• 35%
• 65%

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

• 20%
• 27%
• 46%
• 53%

What is the percent by mass of oxygen in MgO?

• 20%
• 40%
• 50%
• 60%

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

• 24%
• 49%
• 51%
• 65%

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

• 24%
• 49%
• 51%
• 65%

How many molecules are there in 0.04 moles of CaF?

• 2.4 x 10²³
• 2.4 x 10²²
• 2.36
• 1450

What is the percent composition on Oxygen in NO₂? (rounded)

• 40%
• 50%
• 60%
• 70%