Answer:
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.
