Answer. When a reversible reaction begins; forward reaction takes place very fastly and reverse reaction takes place very slowly gradually for rate of forward reaction slows down and rate of reverse reaction speeds up. Ultimately a stage comes when, only rates of forward and reverse reactions become equal to each other but take place in opposite directions and reaction does not stop this is called dynamic equilibrium state. Dynamic means reaction is still continuing. At dynamic equilibrium state:
Rate of forward reaction = Rate of reverse reaction
Graph showing the rate of forward and reverse reactions and establishment of equilibrium state