Benzene on ozonolysis followed by reaction with $\mathrm{Zn}+{\mathrm{H}}_2\mathrm{O}$ gives 

When one molecule of ozone and all three double bonds in benzene are combined, the result is a triozonide derivative. The stable intermediate produced by this reaction is the triozonide intermediate. The solution will then have $Zn+H_{2}O$ added to it.$Zn$ metal is a reducing agent. As a result, if an ozonide intermediate is subjected to reductive workup, the two carbon atoms that are linked to oxygen atoms in an ozonide group are changed into functional aldehyde groups.