The density of a liquid is the ratio of its mass to its volume. It is an extensive property even though mass and volume are both intensive properties. At a certain temperature and pressure, the density of a liquid is constant. The solution is as follows:
Density = Mass of liquid/Volume of liquid
Mass of liquid = Mass of liquid and cylinder - Mass of cylinder
Mass of liquid = 12 g - 10.8 g = 1.2 g
Density = 1.2 g/7.4 mL
Density = 0.162 g/mL
