30.

If 30.1 grams of Hg combines completely with 12.0 grams of Br to form a compound, what is the percent composition of Hg in the compound?

A.

60.1%

B.

39.9%

C.

71.5%

D.

28.5%

Question

30. 	

If 30.1 grams of Hg combines completely with 12.0 grams of Br to form a compound, what is the percent composition of Hg in the compound?

 A. 	
	
	 

60.1%
 
	
B. 	
	
	 

39.9%
 
	
C. 	
	
	 

71.5%
 
	
D. 	
	
	 

28.5%

anonymous · Answer

C. 71.5% - Because the total mass of both would be 30.1 g + 12.0 g = 42.1 g. 
If you want to know the percentage the 30.1 (Hg) is out of 42.1 g (both), you just do 30.1/42.1 = 0.7149, which would be the same as 71.5%