water

[ttv]

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?

(A)16
(B)72
(C)112
(D)128
(E)142



-thanx

[StarDust845]

D.

(16/18 ) * 144.

[II]

Some more explanation behind the answer for you ....

Ratio of hydrogen to oxygen is 2:16
So we know for every 2 grams of hydrogen there will be 16 grams of oxygen. In this instance we will have a total of 18 grams.
So in every 18 grams of water, there will be 16 grams of oxygen.

Can be written as a fraction: 16/18 (16 parts of the 18 whole)

So we want to find how many grams of oxygen there are in 144 grams of water.
We are looking for x/144 (x parts of the 144 whole).

So we use 16/18 and x/144 and cross multiply.

16x144 = 18x
2304=18x
So x = 2304/18 = 128

Answer is D.

P.S. Where did you get this question from ?

Thanks