Given that,
Density of the liquid, d = 3 g/ml
Volume, V = 20 mL
To find,
The mass of the liquid.
Solution,
The density of an object is given by its mass divided by volume such that,
d = m/V
m is mass
m = d×V
Put all the values,
m = 3 g/mL × 20 mL
= 60 grams
Hence, the mass of a liquid is 60 grams.