3. [20] For the completely reversible reaction below, the first order rate constant for the forward reaction is 500s1 and the equilibrium constant is 10 . A=B (the equal sign can be interpreted here as a two-sided arrow) a) What is the rate constant for the reverse reaction? b) Determine the concentration of A as a function of time for a system with initial concentrations of [A]0= 1mM and [B]0=0. Give your answer as an equation for [A] as a function of time