Answer
See the answer below.
Work Step by Step
a) The 1/[NH4NCO] vs t plot has a better straight-line fit than ln [NH4NCO] vs t, so the reaction is of second-order.
b) The regression is: $1/C=0.0109\dot{}t+2.211=kt+1/C_0$, so $k=0.0109\ min^{-1}$ and $C_0=0.452\ M$
c) $1/(0.5\dot{}0.452\ M)=0.0109\dot{}t+2.211\rightarrow t=203.1\ min=t_{1/2}$
d) $1/C=0.0109\dot{}t+2.211\rightarrow C(12\dot{}60)=0.0994\ M$
