For the conversion of ozone to oxygen in the atmosphere,nitric oxide in the gaseous phase acts as:

Fill in the blanks:
$1.$ $TiCl_4$ with $Al(CH_3)_3$ is called ............ catalyst.
$2.$ In the Haber process,ammonia is produced from a mixture of ............ .

In the oxidation of oxalic acid by $KMnO_4$,the color of $KMnO_4$ disappears slowly at the start of the reaction but disappears very fast afterwards. This is an example of:

Which one of the following statements is not correct?

$A$ chemical reaction is catalyzed by a catalyst $X$. Hence $X$

$A$ catalyst is a substance that ......