Question

which feature is unique to group 18 nonmetals? (1 point)
they follow a different pattern of reactivity
they are very reactive.
they are very nonreactive.
they have more exceptions to reactivity rules

Explanation:

Group 18 nonmetals are noble gases. Noble gases have a full valence electron shell, which makes them very nonreactive under normal conditions. Other groups may have different reactivity patterns, but being very nonreactive is a unique and defining feature of Group 18 nonmetals.

Answer:

They are very nonreactive.