When 9.44g of calcium is heated in air,13.22g of calcium oxide is formed.What is the percent by mass of oxygen in this compound?
A)28.6%
B)40.0%
C)71.4%
D)13.2%

Question

Quizplus · Accepted Answer

The mass of oxygen in the compound can be found by subtracting the mass of calcium from the mass of calcium oxide: 13.22g - 9.44g = 3.78g. The percent by mass of oxygen is then (3.78g / 13.22g) * 100% = 28.6%.

When 944g of Calcium Is Heated in Air,13