what is the difference between equilibrium constant(Kc) AND reaction quotient(Qc)??

"Kc" is the equllibrium constant of a particular reaction when the reaction actually attains equllibrium.It is always fixed & constant for a particular reaction at a particular temperature.But "Qc" is a variable ratio just like "Kc" at any other state, other than the equillibrium state of a reaction. When only Qc=Kc then only reaction attains equllibrium and that,s the basic difference.

Please approve if you like.

Kc--> is the equilibrium constant.

         Its the ratio of activity (or concentration) of products by reactants raised to thier stoichiometric coefficients (!!!AT              EQUILIBRIUM.!!!!)

         It is constant for a given reaction at a given temperature.

Qc-->It is the reaction quotient.

        Its the ratio of activity (or concentration) of products by reactants raised to thier stoichiometric coefficients (!!!NOT NECESSARILY AT EQUILIBRIUM.!!!!)

        Its value varies as the reaction proceeds....

sir, what do u mean by other state??

HERE,any other state means any other time of consideration for a reaction when it is taking place, except that time or point of time when reaction attains equillibrium. Hope you understand it!