The problem asks us to find the relative atomic mass of oxygen, given the actual mass of an oxygen atom is $2.66 \times 10^{-23}$ g and the actual mass of a carbon atom is $1.99 \times 10^{-23}$ g.

1. Problem Description

The problem asks us to find the relative atomic mass of oxygen, given the actual mass of an oxygen atom is $2.66 \times 10^{-23}$ g and the actual mass of a carbon atom is $1.99 \times 10^{-23}$ g.

2. Solution Steps

The relative atomic mass is a dimensionless quantity, meaning that we can find it simply by comparing the mass of one element's atom with another.

We are comparing oxygen to carbon, so we want the ratio of the mass of an oxygen atom to the mass of a carbon atom.

Relative atomic mass of oxygen $= \frac{\text{Mass of an oxygen atom}}{\text{Mass of a carbon atom}}$

Given the values, the relative atomic mass of oxygen is:

$\frac{2.66 \times 10^{-23} \text{ g}}{1.99 \times 10^{-23} \text{ g}}$

$\frac{2.66}{1.99} \approx 1.3366834$

The relative atomic mass of oxygen is approximately $1.3366834$ relative to carbon.

Because carbon is considered to be equal to 12 atomic mass units, we need to multiply that by 12 in order to have oxygen relative to the current standard.

Relative atomic mass of oxygen = $1.3366834 \times 12 \approx 16.04$

3. Final Answer

The relative atomic mass of oxygen is approximately 16.04.