A materials student models two solid alloys of a hypothetical metal \(M\), which has an atomic radius of \(140\text{ pm}\) and a molar mass of \(56\text{ g/mol}\). In the model, a solute is predicted to occupy a substitutional site when \(0.85\leq \dfrac{r_{\text{solute}}}{r_M}\leq 1.15\), whereas a solute can fit into an ideal octahedral interstitial site when \(\dfrac{r_{\text{solute}}}{r_M}\leq 0.414\).

Alloy	Composition	Solute radius	Solute molar mass
\(P\)	Replace \(1\) of every \(10\) atoms of \(M\) with \(X\)	\(133\text{ pm}\)	\(52\text{ g/mol}\)
\(Q\)	Add \(1\) atom of \(Y\) for every \(10\) atoms of \(M\)	\(56\text{ pm}\)	\(16\text{ g/mol}\)

Measurements indicate that the two alloys have the same volume per \(10\) original host-lattice sites. All other microstructural features that affect malleability are held constant. Which row correctly compares the density and malleability of the two alloys?