Question

Which of the following has the highest relative density?
(A) water
(B) oil
(C) mercury
(D) glass

Answer 1

Here, we will use the formula for relative density. The relative density is referred to as the density of the liquid solid or gas to the ratio of the standard liquid solid or gas. Water is taken as the standard substance for a liquid or gas. Air is taken as the standard substance for gases.

Complete step by step answer:
We write the formula for relative density.
$Rd = \dfrac{{{\rho _s}}}{{{\rho _{st}}}}$
Here, Rd is the relative density, ${\rho _s}$ is the density of the substance and ${\rho _{st}}$ is the density of standard or reference substance.
We know that the relative density of water is 1.
It is known that the relative density of oil is always less than that of water. This is the reason that oil floats on water. The relative density of water ranges from 0.84 to 0.96.
We know that the absolute density of mercury is $13.6\;{\rm{g/c}}{{\rm{m}}^{\rm{3}}}$ and the absolute density of water is $1\;{\rm{g/c}}{{\rm{m}}^{\rm{3}}}$. Then the relative density of mercury is given as,
$\begin{array}{c} R{d_m} = \dfrac{{13.6}}{1}\\\ = 13.6 \end{array}$
The relative density of the mercury is 13.6
We know that the density of glass material is $2.5\;{\rm{g/c}}{{\rm{m}}^{\rm{3}}}$. Then, the relative density of glass is given as,
$\begin{array}{c} R{d_g} = \dfrac{{2.5}}{1}\\\ = 2.5 \end{array}$
The relative density of glass is 2.5
Now, we know the relative density of all four given substances .The comparison of the relative density of all substances gives us that the relative density of mercury is maximum.

So, the correct answer is “Option C”.

Note:
We can use the relative density of a substance to know the value of the density of an unknown substance. The geologists also use the relative density concept to determine the mineral content of the rocks.