Question

The weight of a solid is $80\text{g}$ in air and $50\text{g}$ in a liquid of relative density $1.5$. Calculate the relative density of the solid.

• A. $4$
• B. $6$
• C. $8$
• D. $2$

Answer 1

The correct option is A $4$

Given:

Mass of the solid in air $m_1=80\text{g}$
$⟹$ Weight of the solid in air $W_1=80\text{gf}$

Mass of the solid in the given liquid $m_L=50\text{g}$
$⟹$ Weight of the solid in the given liquid $W_L=50\text{gf}$

Loss in the solid's weight, $W^{\ast }=W_1-W_L=80-50=30\text{gf}$

Relative density of the liquid $R{D}_{\text{L}}=1.5$

We know that the relative density of a solid can be calculated if we know its weight in air and in a liquid of known relative density as:
$RD=\frac{W_1}{W^{\ast }}\times R{D}_{\text{L}}=\frac{80}{30}\times 1.5=4$