Question

to maintain chemical equilibrium, reactions must be in a(n) (1 point)
closed system
variable system
open system
changing system

Explanation:

Chemical equilibrium requires a system where reactants and products can't escape or be added (no matter exchange). A closed system prevents matter from entering/leaving, allowing forward and reverse reactions to balance. Variable, open, or changing systems would disrupt this balance as matter or conditions change.

Answer:

A. closed system