The mass of a raindrop is given as \(50 \, \text{mg}\). To convert this to kilograms, we use the conversion factor \(1 \, \text{mg} = 10^{-6} \, \text{kg}\).
\[
50 \, \text{mg} = 50 \times 10^{-6} \, \text{kg} = 5.0 \times 10^{-5} \, \text{kg}
\]
The mass of 1 mole of raindrops is given as \(3.0 \times 10^{23} \, \text{g}\). To convert this to kilograms, we use the conversion factor \(1 \, \text{g} = 10^{-3} \, \text{kg}\).
\[
3.0 \times 10^{23} \, \text{g} = 3.0 \times 10^{23} \times 10^{-3} \, \text{kg} = 3.0 \times 10^{20} \, \text{kg}
\]
The mass of the Pacific Ocean is given as \(7.08 \times 10^{20} \, \text{kg}\). We are given that there are 23.5 moles of raindrops in the Pacific Ocean.
To find the number of moles, we use the formula:
\[
\text{Number of moles} = \frac{\text{Mass of the Pacific Ocean}}{\text{Mass of 1 mole of raindrops}}
\]
Substituting the given values:
\[
\text{Number of moles} = \frac{7.08 \times 10^{20} \, \text{kg}}{3.0 \times 10^{20} \, \text{kg}} = 23.6
\]