Question: When heated, mercuric oxide decomposes to form liquid mercury and oxygen. A scientist heated 10 grams (g) of mercuric oxide and formed 9.3 grams of liquid mercury. How many grams of oxygen were formed?

  Options: 
 A. 0.7 g
 B. 9.3 g
 C. 10.0 g
 D. 19.3 g
Answer: A