JEE Main · 2004 · 24 Apr 2004 · Offline · Solid State

This is the classic case of tin pest. The ordinary white, metallic form of tin, $\beta$-tin, is stable only above about $13^{\circ }\text{C}$; below that it slowly turns into grey $\alpha$-tin, a crumbly non-metallic powder. The transformation is a change in the crystal structure of the element itself, from the tetragonal white form to the diamond-type cubic grey form, and the bitter Alpine cold is what set it off in the soldiers' buttons.