what is the mass of 18.7 cm3 of gasoline (density 0.680 g/cm3)?

Answer 1

It is 12.716g

The units of measurement (g)rams and cm3(cubic centimeters lend a clue.

You've got the density of gas (0.68 g/cm3) and you know you have 18.7cm3 of gas.

mass in (g)rams = density (given in g/cm3) X volume (given in cm3)

so multiply density times volume and notice that cm3 units which are in the numerator (on top) in the volume and in the denominator in the density, cancel out.

mass in (g)rams = (0.680g/cm3) X (18.7cm3)

mass in (g)rams = 12.716g

Answer 2

density = mass/volume

mass = density * volume

mass = 0.68*18.7 g

Answer 3

12.716g