Please answer all 3

1. In a reaction, A+B+CD, it is found that the reaction is second order in terms of A, first order in terms of B, and half order in terms of C. What happens to the rate if the concentrations of A and C are doubled and B remains the same? 2. What do catalysts change in a reaction? Does a catalyst change the activation energy of a reaction? 3. What two conditions of reactants must be met for a reaction to proceed