CHM 101 questions

For a certain first order reaction, it is found that it takes 156 seconds for the concentration of reactant to fall from 0.100 M to 0.0500 M. How much time would it take for the concentration of reactant to fall from 0.0500 M to 0.0250 M?

a. 165 seconds b. 76 seconds c. 156 seconds d. 98 seconds

A catalyst functions by:

a lowering the energy of the reactants.

b. lowering the energy of the products.

c. decreasing the rate of the reverse reaction.

d. providing a reaction path with a lower activation energy