Question #44992

An optically active aldopentose $\textbf{P}$ undergoes the Kiliani-Fischer chain extension sequence: (i) $\ce{HCN / KCN}$, (ii) $\ce{H3O+}$, $\Delta$, (iii) $\ce{Na(Hg), H2O}$, pH 3-5. This yields a mixture of two aldohexoses, $\textbf{Q}$ and $\textbf{R}$. When $\textbf{Q}$ and $\textbf{R}$ are separately heated with excess phenylhydrazine ($\ce{PhNHNH2}$) in an acetate buffer at $100^\circ\text{C}$, they consume $x$ and $y$ moles of phenylhydrazine per mole of sugar, respectively, to form osazone derivatives $\textbf{O}_Q$ and $\textbf{O}_R$. Which of the following correctly describes the relationship between $\textbf{O}_Q$ and $\textbf{O}_R$, the values of $x$ and $y$, and the number of chiral carbons in $\textbf{O}_Q$?