Question

Which of the following gas is the densest of all?
A. Air
B. Chlorine
C. Ozone
D. Argon

Answer 1

Hint: Density is defined as the ratio of mass and volume. This means density of an element is directly proportional to mass of the element and inversely proportional to volume of the element. So find the molar masses of the given options in the questions at appropriate temperature and pressure.

Complete step by step answer:
We are given to find the gas which is densest among all the given options.
First one is Air. It might seem like air has no mass but it has and air is a mixture of 78% Nitrogen, 21% Oxygen and the rest 1% are gases with negligible masses.
So, find the molar masses of ${O_2}$ and ${N_2}$
The molar mass of Oxygen is $16g/mol$
The molar mass of Nitrogen is $14g/mol$
The average molar mass is equal to the sum of the mole fractions of each gas multiplied by the molar mass of that particular gas.
Therefore, the molar mass of Air is $28.9g/mol$
Second one is Chlorine. The molar mass of chlorine is $35.45g/mol$
Third one is Ozone. The molar mass of Ozone is $48g/mol$
Fourth one is Argon. The molar mass of Argon is $39.94g/mol$
As we can see out of Air, Chlorine, Ozone and Argon, Ozone has the highest molar mass.
But the densities of Air, Chlorine, Ozone, and Argon are 1.225, 2.994, 1.661, and 2.14 at 15 degree centigrade.
Therefore, the density of Chlorine is the highest which means Chlorine is the densest of all.
From the options given, Option B is correct, which is Chlorine is the densest gas out of all given options.

Note:Density is mass of a unit volume of a material. Density (D) can be given as $D = \frac{m}{V}$ where m is the mass of the substance and V is the volume of the substance. The units of density are $g/c{m^3}orkg/{m^3}$