Answer:
As it gets hydrolyzed easily.
Explanation:
The isocyanic acid may get polymerizes easily into cyanuric acid and a polymer cyamelide
Also, even at 0 °C temperature it may react with mositure and gets hydrolyzed into ammonia an carbon dioxide. Thus we generally prepare it in situ. Even after synthesis it is stroed at dry ice or liquid nitrogen at very low temperature.
The lewis structure is shown in the figure.