Question

Given, $100$ times density $\left( {in\;gm\;{L^{ - 1}}} \right)$ of ${O_2}$ at $STP$ is?

Answer 1

Hint: Density is termed as mass per unit volume of the material substance. Thus, the formula for density is:
$d = \dfrac{M}{V}$
Where, $d$ is density, $M$ is mass and $V$ is volume. The unit which is commonly used to express density is grams per cubic centimetre.

Complete answer:
Density is the physical property which shows the denseness of material in a specific given area. It is the mass of the unit volume of a given object. It is a specific characteristic of physical property for a particular object. Thus, in qualitative form, it tells how much heavy an object is at constant volume.
Tell us take a simple example of a leaking oil tank in the ocean. The oil drops start to float on the water because they have less density than that of water. This indicates that if a substance is less dense than another substance then it will float on that substance and when it will be less dense than that substance then it will sink.
The unit of density can also be expressed in kilograms per cubic metre. We can calculate the mass by using density if we know the volume of the substance. For which we can use:
$M = Vd$
Similarly, we can find the value of volume by using density formula if we know the mass of the substance by:
$V = \dfrac{M}{d}$
As, we know that one mole of ${O_2}$ whose weight is $32\;gm$ and it occupies $22.4\;L$ volume at $STP$.
Thus,
$density = \dfrac{{mass}}{{volume}}$
$ \Rightarrow \dfrac{{32}}{{22.4}} = 1.43\;gm\;{L^{ - 1}}$
Therefore,
$100d = 143$

Note:
Remember by using the density formula we can find the weight of the body. It can simply be obtained by multiplying the mass by acceleration due to gravity. Particle density refers to the number of particles of unit volume and it is represented by $n$.