No2 and n2o4 undergo the reaction shown. when a sealed container of no2 reaches chemical equilibrium, which must be true

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Correct Option H. Rates of forward and reverse reactions are equal.

Reason:
The reactant NO2 and product N2O4 are in equilibrium. One of the important criteria for the equilibrium system is that the rates of forward and backward reactions are same. Due to this, the rate at which reactant gets converted into product, at the same rate, products gets converted back into reactant. Thus, at any given time, there is always an effective concentration of  both reactant and product in the reaction vessel