Answer:
0.775 g/cm³
Step-by-step explanation:
The given parameters are;
The mass of the alcohol = 21 g
The density of the of the alcohol = 0.7 g/cm³
The mass of water with whichit is mixed = 10 g
The density of water = 1.0 g/cm³
Therefore, the mass of the mixture, m = 21 g + 10 g = 31 g
Volume = Mass/Density
The volume of the alcohol = 21 g/(0.7 g/cm³) = 30 cm³
The volume of the water = 10 g/(1.0 g/cm³) = 10 cm³
Therefore, the volume of the mixture, V = 30 cm³ + 10 cm³ = 40 cm³
The density of the mixture, ρ = (Mass, m)/(Volume, V) = m/V
∴ ρ = (31 g)/(40 cm³) = 0.775 g/cm³
The density of the mixture, ρ = 0.775 g/cm³.