Zero order reaction

For the zero order decomposistion of HI on a gold surface it takes 1.0 seconds for the concentration of HI to drop from 0.335M to 0.285M.
HI(g)---> 1/2H2(g)+1/2I2

I need to know what is the rate constant for the reaction, how long will it take for the concentration of a 0.650M solution to drop to 0.0100M, and what is the half life of a 0.400M solution