Finding Percents

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

• 20%

• 27%

• 46%

• 53%

Find the percent composition of CaCl₂?

• Ca: 36.11%; Cl: 63.88%

• Ca: 53.12%; Cl: 100%

• Ca: 36.11%; Cl: 83.56%

• Ca: 46.11%; Cl: 63.88%

What is the percent composition by mass of sulfur (S) in the compound MgSO₄?

• 20.22%

• 19.85%

• 26.64%

• 28.64%

What is the percent composition by mass of hydrogen in water (H2O)?

• A) 11.19%

• B) 8.33%

• C) 5.55%

• D) 10.00%

In a chemical reaction, if 20 grams of a reactant is used and 5 grams of product is formed, what is the percent yield?

• A) 25%

• B) 50%

• C) 75%

• D) 100%

Tags

NGSS.HS-PS1-7

A solution contains 15 grams of salt dissolved in 85 grams of water. What is the percent concentration of salt in the solution?

• A) 15%

• B) 17.65%

• C) 20%

• D) 25%

If a metal alloy is composed of 70% copper and 30% zinc, what is the percent of copper in 200 grams of the alloy?

• A) 70%

• B) 60%

• C) 50%

• D) 40%

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

• A) 27.29%

• B) 33.33%

• C) 44.44%

• D) 72.71%

Tags

NGSS.HS-PS1-7

A scientist finds that a sample contains 40% iron and 60% oxygen by mass. What is the percent of iron in a 500 gram sample?

• A) 40%

• B) 50%

• C) 60%

• D) 70%

In an experiment, a student finds that 10% of a 200 gram sample is sulfur. How many grams of sulfur are in the sample?

• A) 10 grams

• B) 20 grams

• C) 30 grams

• D) 40 grams