How is rate constant related to conc. of the reactant ?

If 'a' is the initial concentration of a substance which reacts according to zero order kinetic and k k'is rate constant, the time for the reactant to go to completion is,

For a reaction the initial conc. of the reactant is 0.25 M. If the rate constant of the reaction is 2.5 xx10^-2 sec^-1 , find the initial rate of the reaction.

In a first order reaction, A to B , if k is rate constant and the initial concentration of the reactant A is 0.5 M, then half-life is

For a 1st order reaction t_(1/2)=2 min. How long will it take to reach 25% of the initial conc. of the reactant ?

For a 1st order reaction when rate of reaction is plotted conc. of reactant a straight line is obtained whose slope is 2.5. What is its rate constant.

Derive an expression for rate constant of zero order reaction. For the reaction, 2NO+CI_2rarr2NOC1 , the rate of reaction is increased by a factor of 8, by doubling the conc. of both. Again doubling the conc. of Cl_2 only doubles the rate. Find order of the reaction w.r.t NO and Cl_2 .