[tex]\textbf{1.3877}\times\textbf{10}^{\textbf{17}}\textbf{ mol}[/tex]
Step-by-step explanation:
We are considering [tex]2.5\times10^{18}\text{ }g[/tex] of water.
We know that each mole of a substance weights equal to the substances' molar weight.
The molar weight of water ( [tex]H_{2}O[/tex] ) is [tex]18.0153\text{ }\frac{g}{mol}[/tex]. This value is a standard and hence can be found from charts.
[tex]\text{Number of moles of compound = }\dfrac{\text{Weight of sample given}}{\text{Molar weight of compound}}[/tex]
[tex]\text{Number of moles of water present = }\dfrac{2.5\times10^{18}\text{ }g}{18.0153\text{ }\frac{g}{mol}}\text{ = }1.3877\times10^{17}\text{ }mol[/tex]
∴ Number of moles of water = [tex]1.3877\times10^{17}\text{ }mol[/tex]