On a topographic map every fifth contour is darkened. what is this line call? a. key b. slope c. benchmark d. index contour someone plz hurry

16. in a reaction that has reached equilibrium, a. the forward and reverse reactions are occurring at the same rate. b. the reactants and products are in equal concentrations. c. the forward reaction has gone further than the reverse reaction. d. there are equal numbers of atoms on both sides of the equation. e. a, b, and d are correct.