Wilhelm Ostwald redefined the action of

What is the role of a catalyst in a catalysed reaction?

Which is True $(T)$ and False $(F)$ of the following statements?
$1.$ Catalysts do not participate in the reaction.
$2.$ The catalyst increases the rate of reaction.
$3.$ Catalyst decreases the rate of reaction.
$4.$ Catalyst changes the pathway of reaction.

Which catalyst is used for oxidation of $SO_2$ to $SO_3$ in the lead chamber process for the manufacture of sulphuric acid?

Hydrogenation of vegetable oils in the presence of finely divided $Ni$ as a catalyst. The reaction is:

Which of the following reactions requires a catalyst?