Question

The ratio of Hydrogen and Oxygen by mass in water is:

• A. 1:8
• B. 8:1
• C. 2:1
• D. 1:2

Answer 1

The correct option is A

1:8

Explanation of the correct answer:

The correct answer is option A:

1. Take into account the atomic masses of Hydrogen and Oxygen as well as the quantity of Hydrogen and Oxygen atoms that make up a water molecule.
2. H and O each have atomic weights of 1 g/mol and 16 g/mol, respectively.

The mass ratio of hydrogen and oxygen in ${\mathrm{H}}_2\mathrm{O}$ is,

$\begin{array}{rcl}\mathrm{Ratio}& =& 2\times \mathrm{H}:1\times \mathrm{O}\\ & =& 2\times 1:1\times 16\\ & =& 2:16\\ & =& 1:8\end{array}$

Hence, option (A) is correct, i.e., 1:8.