11. THE P-BLOCK ELEMENTS
Explanation:
Among the given elements tin ( \(Sn\) ) shows the allotropy.
\(\beta\)-tin (the metallic form, or white tin), which is stable at and above room temperature, is malleable. In contrast, \(\alpha\)-tin (nonmetallic form, or gray tin), which is stable below \(13.2^{\circ} C \left(55.8^{\circ} F \right)\), is brittle.