Pure substance definition in chemistry?

What is the relation between concentration of reactants and the rate of chemical reaction?

In a reaction (at equilibrium) that makes more moles of gas than it consumes, what is the effect of increasing the pressure?

How does a catalyst increase the speed of a reaction? a. the catalyst eliminates the activated complex stage, allowing products to form immediately. b. the catalyst lowers the energy level of the reactants, making it easier for them to react. c. the catalyst makes it easier for the activated complex to form, lowering the activation energy. d. the catalyst raises the energy level of the products, making the reaction finish sooner. reset next