Which of the following is necessary to increase the rate of a reaction?

Rate of Reaction ca be increased by applying following changes,

1) Increase in Temperature:
                                            Increase in Temperature results in the increase of Kinetic Energy, Hence, velocity of reactants increases and rate of collisions increases. Thus, more reactants colloid with enough energy to change into products in given time.

2) Decrease in Activation Energy:
                                                     Activation energy is the minimum amount of energy required by reactants to cross the energy barrier to convert into products. Hence, activation energy is decreased by using catalyst.

3) Concentration of Reactants:
                                                 The greater the concentration of reactants, greater is the number of reactants per volume. More reactants in less area increase the probability of collision. Hence, collisions increase and rate of reaction increases.

4) Increasing Surface Area of Reactant:
                                                               Greater the surface area greater is the rate of reaction.