Which of the following is not an oxidation-reduction reaction?
Upper X e upper F subscript 6 (s) right arrow upper X e upper F subscript 4 (s) plus upper F subscript 2 (g).
2 upper C s (s) plus upper I subscript 2 (g) right arrow 2 upper C s upper I (s).
2 upper H subscript 2 upper S upper O subscript 4 (a q) plus 2 upper B a (upper O upper H) subscript 2 (a q) right arrow 2 upper B a upper S upper O subscript 4 upper H subscript 2 upper O (l).
Upper Z n (s) lus 2 upper A g upper N upper O subscript 3 (a q) right arrow upper Z n (upper N upper O subscript 3) subscript 2 (a q) plus upper A g (s).