1 what is the half-life for the reaction starting at t 0 s

Question

A student obtained the following data for the conversion of methyl isonitrile to acetonitrile in the gas phase at 250 °C.

CH₃NC(g)--->CH₃CN(g)

(1) What is the half-life for the reaction starting at t = 0 s?_________ s

 

What is the half-life for the reaction starting at t = 169 s?________s

Does the half-life increase, decrease or remain constant as the reaction proceeds? _________(increase/decrease/remain constant)

(2) Is the reaction zero, first, or second order? _______(zero/first/second)

(3) Based on these data, what is the rate constant for the reaction?________ s^-1

(please help me no one yet has been able to answer these questions correcty)