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.
The density of a pure gold is 19.32g/cm3 if the volume is 4.30 cm3 then we can calculate the mass using the formula mass=density x volume mass=19.32*4.30 mass=83.076g