Question

Why is argon used in lamps?
A. Argon forms molecules when electricity is passed through it.
B. Argon is inert and so does not react with the hot filament.
C. Argon is less dense than air.
D. Argon produces light when it burns.

Answer 1

Since there is flow of electricity in the filament inside the bulb due to which there is generation of electrons which is reactive in nature, so we will use a gas which is quite unreactive in nature.

Complete step by step answer:
We know that all noble gases have general electronic configuration $n{s^2}n{p^6}$ except helium which has $1{s^2}$electronic configuration. Except for radon, all other noble gases occur throughout the universe in atomic state.
The noble gases are least reactive due to following reasons-
1. The noble gases except helium ($1{s^2}$) have completely filled $n{s^2}n{p^6}$ electronic configuration in their valence shell.
2. They have high ionisation enthalpy and more positive electron gain enthalpy.
3. The ionization potentials of these gases are very high. Hence the removal of the electron from the outermost shell is very difficult.
4. The atoms of these elements have all electrons paired. Thus, the electrons are not available for sharing with the electrons of other atoms. Hence, hay cannot form covalent compounds.
The bulb filament is made up of tungsten metal. When a lamp glows then there will be a generation of electric light and filament heats at that point when it glows due to which there is a general tendency of the evaporation of the filament. To prevent or slows down the evaporation we will use an inert gas in it
Therefore, the correct option is B.
Note:
In the bulb there is a flow of electricity so we will use an inert type environment which has been provided by Argon. So inside incandescent light bulbs Argon is used while Xenon is used in electronic flash tubes.