The decomposition of $H_2O_2$ can be slowed down by the addition of a small amount of phosphoric acid,which acts as:

$A$ catalyst is a substance which

Which of the following parameters is never affected by using a catalyst during a reaction?

$A$ catalyst is used in a reaction to

Platinized asbestos is used as a catalyst in the manufacture of $H_2SO_4$. It is an example of

Catalysts in the following reactions are:
$(I) CH_3COOCH_{3(l)} + H_2O_{(l)} \rightarrow CH_3COOH_{(aq)} + CH_3OH_{(l)}$
$(II) 2SO_{2(g)} + O_{2(g)} \rightarrow 2SO_{3(g)}$ (Contact Process)
$(III) 2SO_{2(g)} + O_{2(g)} \rightarrow 2SO_{3(g)}$ (Lead Chamber Process)
$(IV) N_{2(g)} + 3H_{2(g)} \rightarrow 2NH_{3(g)}$ (Haber Process)