The mass of an empty density bottle is 30 g, it is 75 g when filled completely with water and 65 g when filled completely with a liquid. Find:

(a) Volume of density bottle,

(b) Density of liquid and

(c) Relative density of liquid.

Mass of empty density bottle (M₁) = 30 g

Mass of bottle with water (M₂) = 75 g

Mass of bottle with liquid (M₃)= 65 g

(a) Mass of water in bottle = M₂ - M₁ = 75 - 30 = 45 g

Density of water is 1 g cm^-3, so volume of density bottle = 45 mL.

(b) Mass of liquid in bottle = M₃ - M₁ = 65 - 30 = 35 g

$\text{Density of liquid}= \dfrac{\text{Mass of liquid}}{\text{ Vol. of liquid}} \\[1em] = \dfrac{\text{35}}{\text{45}} = 0.77 \text{ g cm}^{-3}$

So, density of liquid = 0.77 g cm^-3.

(c) $\text{R.D. of liquid}= \dfrac{\text{Mass of liquid}}{\text{Mass of eq. vol. of water}} \\[1em] = \dfrac{\text{35}}{\text{45}} = 0.77$

So, Relative density of liquid is 0.77.