Finding Percents

What is the percent by mass of sodium in NaCl?

• 39%

• 61%

• 35%

• 65%

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 water (H2O)?

• 33%

• 66%

• 89%

• 11%

In a solution of saltwater, if the mass of salt is 20g and the mass of water is 80g, what is the percent concentration of salt?

• 20%

• 25%

• 30%

• 40%

What is the percent by mass of carbon in carbon dioxide (CO2)?

• 27%

• 33%

• 44%

• 12%

If a metal alloy contains 70g of copper and 30g of zinc, what is the percent composition of zinc in the alloy?

• 30%

• 40%

• 50%

• 60%

What is the percent by mass of hydrogen in methane (CH4)?

• 25%

• 50%

• 75%

• 12.5%

Tags

NGSS.MS-PS1-1

In a chemical reaction, 10g of reactant A is mixed with 90g of reactant B. What is the percent by mass of reactant A in the mixture?

• 10%

• 20%

• 30%

• 40%

What is the percent by mass of nitrogen in ammonia (NH3)?

• 82%

• 14%

• 47%

• 28%

Tags

NGSS.MS-PS1-1

A sample contains 5g of solute and 95g of solvent. What is the percent concentration of the solute?

• 5%

• 10%

• 15%

• 20%