The decomposition of nitramide in aqueous solution at 25 c

Question

The decomposition of nitramide in aqueous solution at 25 °C is  first order in  NH₂NO₂.

NH₂NO₂(aq)N₂O(g) + H₂O(l)

During one experiment it was found that the  NH₂NO₂ concentration dropped from  0.200 M at the beginning of the experiment to  8.18×10^-2 M in  1.716×10⁴ seconds. What is the value of the rate constant for the reaction at this temperature? ______ s^-1

The gas phase decomposition of dinitrogen pentoxide at 335 K is first order (k = 4.70×10^-3s^-1).

N₂O₅(g)2 NO₂(g) + ½ O₂(g)

How much time is required for 83.7% of the N₂O₅ intially present in a reaction flask to be converted to product at this temperature?  _________s