The correct option is D Both forward and backward reactions occur with the same speed at all times
Chemical equilibrium is dynamic in nature since both forward and backward reactions occur with the same speed (or same rate) at all times. Neither the forward reaction nor the backward reaction has stopped.
Theory:
Characteristics of Chemical equilibrium.
1. Concentrations of reactants and products remain constant with time.
2.No observable or measurable change (like concentration) in the system.
3.Activity only at molecular level.
4.Can only be achieved in a closed container.
Open System
Equilibrium can only be obtained in a closed system where the reaction is carried out in a sealed container and none of the reactants or products are lost.
For example, Iodine crystals break down to form purple Iodine vapour. In an open system, the vapour escapes and the reaction progresses until all of the crystals have vapourised, and all of the vapour has escaped.