1.1. An electric light bulb is shown in Figure 1 below. 

The tungsten filament conducts electricity when the light is switched on and heats up to a high temperature, giving off light.

Figure 1

The bulb has a closed atmosphere containing argon only. 

What reaction would occur if air was used instead of argon?

1.2. With reference to the electronic structure of the argon atom, explain why it is used in light bulbs.