Which of the following reactions is NOT a redox reaction? Question 25 options: SO3(g) + H2O(l)  H2SO4(aq) Al(s) + 3Ag+(aq)  Al3+(aq) + 3Ag(s) Ba(s) + Cl2(g)  BaCl2(s) H2(g) + O2(g)  H2O(g) Al(s) + Fe2O3(s)  Fe(s) + Al2O3(s)

SO3(g) + H2O(l) > H2SO4(aq)

Explanation:

'Redox' is a term used to describe reduction and oxidation since the both are complementary processes, one can not occur without the other.

A redox reaction is one in which there is a change in the oxidation number of the reactants from left to right of the reaction equation.

If we looks at the reaction;

SO3(g) + H2O(l) > H2SO4(aq)

There was no change in the oxidation numbers of species from left to right of the reaction equation. For instance, the oxidation state of sulphur is +6 on both sides of the reaction equation hence it is not a redox reaction.