Answer
The liquid is ethanol with the density 0.789 g/$cm^{3}$.
Work Step by Step
1- Find the density of the liquid with mass 6.71 g and volume 8.5mL.
2- d = $\frac{m}{v}$
d = $\frac{6.71 g}{8.5 mL}$
d = 0.789 $\frac{g}{mL}$
3- Convert the mL to $ cm^{3 }$at the density 0.789 $\frac{g}{mL}$ .
We know that 1 mL = 1 $cm^{3}$
Therefore: 0.789 $\frac{g}{mL}$ = 0.789 $\frac{g}{1cm^{3}}$
0.789 $\frac{g}{mL}$ = 0.789 $\frac{g}{cm^{3}}$
4- Compare the density that we found 0.789 $\frac{g}{cm^{3}}$ to the density of
octane 0.702 $\frac{g}{cm^{3}}$
ethanol 0.789 $\frac{g}{cm^{3}}$
and benzene 0.879 $\frac{g}{cm^{3}}$
( these densities are given in the question) .
We see that the density that we found is the same with the density of ethanol, therefore the liquid is ethanol.
