Question

A sample of pure water, whatever the
source always contains .............. by
mass of oxygen and 11.1 % by mass of
hydrogen.
a. 88.8 b. 18 c. 80 d. 16​

Answer 1

Answer:

The correct answer is 88.8%.

Explanation:

This follows the law of constant composition or definite proportion.

A water molecule (H2O) consists of two hydrogen atoms ( relative mass is 1 for each) and one oxygen atom ( relative mass is 16).

Hence we can interpret this as- there are 2 g of Hydrogen and 16 g of Oxygen present in a sample of 18 g of water. Hence the ratio becomes 2:16 ( H:O) , which is 1 : 8.