Question

What are noble gases? Name all in the order of their increased density.

Answer 1

Hint: Noble gases have filled orbitals. These shells do not have vacancies for new electrons. They rarely react with the other elements. There are a total of six noble gases in the modern periodic table and they are present in group $18$ . They have various applications as they are unreactive.

Complete answer:
The noble gases are the colorless, odorless, tasteless, nonflammable gases. These are also called inert gases or aerogenes. In the modern periodic table, the entire group $18$ belongs to noble gases. They are highly unreactive elements as they are chemically stable compounds. The inertness of noble gases makes them very suitable in applications where reactions are not wanted.
The noble gases in the increasing order of their densities are Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn).
The noble gases are non-reactive, monoatomic gases. They are sparingly soluble in water. They have very low melting and boiling points; because the only type of interaction these elements have is the weak dispersion forces. Their ionization enthalpy is very high and they have more positive electron gain enthalpy. According to some recent studies, noble gases enter into chemical combinations and form some rare chemical compounds. Among all the noble gases Radon is the only radioactive element.
The noble gases emit colored lights when electricity is passed through them. For this reason, they are used as advertising signs. Neon emits orange-red color, Argon emits pale lavender color, Helium emits pale peach color, Krypton emits pale silver color and Xenon emits pale to deep blue color.

Note:
Helium being lighter than air is used to fill balloons and airships, it does not catch fire. Argon is used as filler in light bulbs. Neon is specially used in advertising signs. Krypton is used in lasers for eye surgery and car headlights. Xenon is used in operating rooms, lighthouse lights, etc.