Question

A piece of solid weighs $120\, g$ in air, $80\, g$ in water and $60\, kg$ in a liquid. The relative density of the solid and that of the liquid are respectively

• A. $2, \frac{1}{2}$
• B. $2, \frac{3}{2}$
• C. $3, \frac{1}{2}$
• D. $3, \frac{3}{2}$

Answer 1

Answer: (D)

Relative density of solid
$=\frac{\text{weight in air}} {\text{weight in air — weight in water }}$
$=\frac{120}{120-80}=\frac{120}{40}=3$
Relative density of liquid
$=\frac{\text{weight in air - weight in liquid}} {\text{weight in air - weight in water}}$
$=\frac{120-60}{120-80}=\frac{60}{40}=\frac{3}{2}$