Complex sentence: The inertness of noble gases makes them very suitable in applications where reactions are not wanted; argon is used in lightbulbs to prevent the tungsten filament from oxidizing in the heat; also, helium is breathed by deep-sea divers to prevent oxygen and nitrogen toxicity.
Split into simpler sentences: The inertness of noble gases makes them very suitable in applications where reactions are not wanted. For example: argon is used in lightbulbs to prevent the hot tungsten filament from oxidizing; also, helium is breathed by deep-sea divers to prevent oxygen and nitrogen toxicity.