Q. The soldiers of Napolean army while at Alps during freezing winter suffered a serious problem as regards to the tin buttons of their uniform. White metallic tin buttons got converted to grey powder. This transformation is related to
A) A change in the crystalline structure of tin
B) An interaction with nitrogen of the air at very low temperature
C) A change in the partial pressure of oxygen in the air
D) An interaction with water vapour contained in the humid air
Explanation
(a)
As temperature decreases, white tin ($\beta$-form) changes to grey tin ($\alpha$-form).
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$\alpha$-Sn has a much lower density.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.