List of top Chemistry Questions on Order of Reaction asked in UPSEE

The following graph shows how $(t_{1/2})$ a (half life) of a reactant R changes with the initial reactant concentration $a_0$. The order of the reaction will be

For the reaction $2SO_2 + O_2$ (excess) $\rightarrow\, 2SO_3$ the order of reaction with respect to $O_2$ is