What is the density of an object haveing a mass of 5.0g and a volume of 45.0 cm3

Using the formula d=m/v, we first need to convert 5.0 and 45.0 to their SI unit equivilents. 5.0g is 0.005kg, 45.0cm^3 becomes 0.000045m^3. Therefore, the density of your cube is 0.005/0.000045=111.11 kg/m^3 (5 s. f)

D = m/v = m/v if m=5 gm, v=45cm^3, D=5/45=1/9=0.11 gcm^-3