In the reaction, ${\text{Na}}_{\text{2}}{\text{S}}_{\text{2}}{\text{O}}_{\text{3}} +{\text{ I}}_{\text{2}} \to {\text{ Na}}_{\text{2}}{\text{S}}_{\text{4}}{\text{O}}_{\text{6}} +\text{ NaI}$ , ( not balanced ), which of the following is/are TRUE?

P) ${\text{Na}}_{\text{2}}{\text{S}}_{\text{2}}{\text{O}}_{\text{3}}$ is a reducing agent

Q) Iodine is an oxidising agent

R) It is an example of inter molecular redox reaction

S) In ${\text{Na}}_{\text{2}}{\text{S}}_{\text{4}}{\text{O}}_{\text{6}}$ the average oxidation state of S is (+5/2)