<span>One mole of any material contains 6.02 * 10e23 atoms or molecules. This is the Avogadro number.
So 9.25 * 10e24 atoms are contained in (9.25*10e24 / 6.02 * 10e23) = 15.36 moles. So the answer is that moles of C8H18 is 15.36 moles</span>
The answer is (4) CH3CH2OH and CH3OCH3. You need to figure out which pair has the same molecular formula which means that they have the same number of same atoms. Then you can get the write answer.
It is a mixture because the compounds that make up air e.g. oxygen (o2), Carbon dioxide (co2) and the most important Nitrogen which is an element and makes up 78.09% of air are not chemically bound in the way that compounds are because they can be separated easily and there has been no change in state to any of the compounds or elements in air!hope this helpful!