Which one of the following is not an example of a redox reaction?

a. rusting nail
b. mixing baking soda and vinegar
c. burning wood
d. browning apple core

B. Mixing baking soda and vinegar

Step-by-step explanation:

The reaction is

NaHCO₃ + HC₂H₃O₂ ⟶ NaC₂H₃O₂ + [H₂CO₃] ⟶ H₂O + CO₂

No atoms change their oxidation state. Instead, this is a double decomposition reaction. the product is the unstable carbonic acid, which decomposes at once.

A. is wrong. The overall equation for a rusting nail is

4Fe + 3O₂ → 2Fe₂O₃.

The oxidation number of Fe changes from 0 to +3 and that of O changes from 0 to -2.

C. is wrong. Wood is mostly cellulose, C₆H₁₀O₅.

C₆H₁₀O₅ + 6O₂ ⟶ 6CO₂ + 5H₂O

The oxidation number of C changes from 0 to +4, and that of O in O₂ changes from 0 to -2.

D. is wrong. Apples contain compounds called polyphenols, which are easily oxidized to quinones, and these in turn polymerize to form brown melanin.

We might write the equation as

    C₆H₆O₂ + O₂ ⟶ C₆H₄O₂ + H₂O

polyphenol             quinone

The oxidation number of C changes from +⅓ to 0 and the oxidation number of O in O₂ changes from 0 to -2.

your answer would be “dry”