Why oxygen is called gas?

Oxygen:

• It is represented by the symbol “O” and atomic number is $8$ for oxygen.
• It is a member of the periodic table's chalcogen group.

Gaseous nature of oxygen:

• An intermolecular attraction force exists between the molecules of a substance, which dictates its state at different temperatures.
• Weak intermolecular or Van der Waals forces hold the oxygen atoms together in ${\mathrm{O}}_2$.
• As a result, overcoming these weak forces requires little energy, therefore oxygen has a low boiling point and hence, oxygen is a gas at ambient temperature.