Question

if 1kg of water is mixed with 2 kg of liquid of density 3g/cm3,then the average density of mixture will be
a)2.4
b)1.5
c)2
d)1.8

Answer 1

Density = mass/volume.

For water, the mass is 1kg, which is 1000 gm. It is known that the density of water is 1 $\frac{gm}{cm^{3}}$. Therefore, the volume of water is $\frac{mass}{density} = \frac{1000gm}{1\frac{gm}{cm^{3}}} = 1000 cm^{3}$.

For the liquid, the mass is 2kg = 2000gm, and the density is $3 \frac{gm}{cm^{3}} .$ Therefore, the volume is $\frac{2000gm}{3\frac{gm}{cm^{3}}} = \frac{2000}{3} cm^{3}.$

The average density = $\frac{total \\ mass}{total \\ volume}=\frac{1000+2000}{1000+\frac{2000}{3} }= 1.8 \frac{gm}{cm^{3}}.$