The progress of the reversible reaction A Two arrows stacked on top of each other. The top arrow points to the right. The bottom arrow points to the left. B is

Question

The progress of the reversible reaction A Two arrows stacked on top of each other. The top arrow points to the right. The bottom arrow points to the left. B is shown in the graph below. Which line represents the point at which the reaction reaches equilibrium?

The graph shows the concentration of two gases, A and B, during a reversible reaction. Line P represents where the gases (A and B) begin. As the reaction progresses, the concentration of A decreases while the concentration of B increases. The curves cross and the concentrations of both A and B (represented by line Q) eventually level out as the reaction progresses (represented by line S). Line R represents the midpoint between both gasses throughout the reaction.

line P
line Q
line R
line S

Answer 1

Although you did not provide the diagram, the one with both arrows of equal magnitude (length) in opposite directions would be the equilibrium system.