In which of the following reactions heterogeneous catalysis is involved?
(i) `2SO_(2)(g)+O_(2)(g) overset(NO(g))(to) 2SO_(3)(g)`
(ii) `2SO_(2)(g) overset(Pt(s))(to) 2SO_(3)(g)`
(iii) `N_(2)(g)+3H_(2)(g) overset(Fe(s))(to) 2NH_(3)(g)`
(iv) `CH_(3)COOCH_(3)(l)+H_(2)O(l) overset(HCl(l))(to)CH_(3)COOH(aq)+CH_(3)OH(aq)`

Options

A. (ii),(iii)
B. (ii),(iii) and (iv)
C. (i),(ii) and (iii)
D. (iv)

Answer

A

Explanation

Reaction in which catalyst is in different phase than other (reactants and products) is known as heterogeneous catalysis.
(ii) `2SO_(2)(g) overset(pt(s))to 2SO_3 (g)`
Here, reactant `SO_(2)` and product `SO_(3)` are in gaseous phase while platinum is in solid phase. So, this reaction represents a heterogeneous catalysis.
(iii) `N_(2)(g)+3H_(2)(g) overset(Fe(s))to 2NH_3 (g)`
Similarly, here `N_(2)` and `H_(2)` reactants are in gaseous phase while `NH_(3)` is in solid phase. Whereas in other reactions catalyst is in same phase with reactant (s) and product (s).