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 144 grams of water?  Answers
A) 16 B) 72 C) 112 D) 128 E) 142
See H/O = 2 / 16   Add 1 to both sides:   H/O + 1 = 2/16 + 1   Take LCM   (H+O)/O = (2+16)/16   Water/O = 18/16   Now that we have the Water to Oxygen ratio, put in the amount of water i.e. 144 gm   =&gt;O= 144*16/18= 
<gadget id="calculator">144*16/18</gadget>
<output>128</output>
128   ANSWER:128
<result>D</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 144 grams of water?