Water consists of hydrogen and oxygen, and the approximate ratio, by mass, of hydrogen to oxygen is 2:16. Approximately how many grams of oxygen are there in 162 grams of water?
Choose the correct choice from the following answers.
A) 16  B) 72  C) 112  D) 128  E) 144
Solution:   We are given that the ratio of hydrogen to oxygen in water, by mass, is 2 : 16. Using our ratio multiplier we can re-write this as 2x : 16x. We can now use these expressions to determine how much oxygen is in 162 grams of water.   2x + 16x = 162   18x = 162   x = 9   Since x is 9, we know that there are 16 x 9 = 144 grams of oxygen in 162 grams of water.   Answer 144.
<result>E</result>
Water consists of hydrogen and oxygen, and the approximate ratio, by mass, of hydrogen to oxygen is 2:16. Approximately how many grams of oxygen are there in 162 grams of water?