Question

A beaker of 5 liter is filled with a liquid. The value of the relative density is $0.8$. Find the mass of the liquid.
Density of water$=1gc{m}^{-3}$

• A. $1kg$
• B. $2kg$
• C. $3kg$
• D. $4kg$

Answer 1

The correct option is D $4kg$

Given:
Volume of liquid,
$V=5l$
$V=5000c{m}^3$
$\because 1l=1000cm{}^3$
Relative density, ${\rho }_r$ $=0.8$
Density of water, ${\rho }_w=1gc{m}^{-3}$

Let's assume that the density of liquid is $\rho$ and mass of liquid is $M$.

From defintion of relative density,
${\rho }_r=\frac{\rho }{{\rho }_w}$

From defintion of density,
$\rho =\frac{M}{V}$

$⟹M=V\times \left({\rho }_r{\rho }_w\right)$
$M=5000\times 0.8\times 1$
$M=4000g=4kg$