Question

________________________________________ is a reaction in which the conversion of reactants into products and the conversion of products into reactants can happen at the same time.

Answer 1

Answer is: reversible reaction.
The concentrations of reactants and products in an equilibrium mixture are determined by the equilibrium constant K.
When writing chemical equations for reversible reactions, two arrows are used, for example: NH₄Cl(s) ⇆ NH₃(g) + HCl(g) or
CuSO₄(s) + 5H₂O(l) ⇆ CuSO₄·5H₂O(s).