Compound P and R upon ozonolysis produce Q and S, respectively. The molecular formula of Q and S is ${\mathrm{C}}_8{\mathrm{H}}_8\mathrm{O}$ . Q undergoes Cannizzaro reaction but not haloform reaction, whereas S undergoes haloform reaction but not Cannizzaro reaction.

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Isomers of hexane, based on their branching, can be divided into three distinct classes as shown in the figure.

The correct order of their boiling point is

The major product formed in the following reaction is

In the reaction scheme shown below, $\mathrm{Q}, \mathrm{R},$ and $\mathrm{S}$ are the major products.

 The correct structure of