Question

The second reaction in the formation of sulfuric acid occurs slowly.

Answer 1

Answer: The correct option is $NO_2(g)$

Explanation:

A catalyst is defined as the chemical species that increases the reaction rate but does not participate in it and is left behind after the completion.

A homogeneous catalyst is one that is present in the same phase as the reactants and products.

A heterogeneous catalyst is one that is present in different phase as that of reactants and products.

For the given chemical reaction:

$2SO_2(g)+O_2(g)\rightarrow 2SO_3(g)$

As all the reactants and products are in gaseous state so, the homogeneous catalyst must also be in the gaseous state only.

Hence, the correct option is $NO_2(g)$