Explain how an element that does not react easily with other elements can be useful.

Elements that are unreactive can be useful for 'isolating' other volatile elements. For example, an element may be highly reactive with oxygen, so keeping it in air is not a safe option. In such cases, it may be useful to have a noble gas to store the element safely and ensure its stability. It may also have a purpose in experiments where it may act as a controlling agent or a container for the other reactions.