Question
The soldiers of Napolean army while at Alps during freezing winter suffered a serious problem as regards to the tin buttons of their uniforms. White metallic tin buttons got converted to grey power. This transformation is related to
A.
a change in the partial pressure of oxygen in the air
B.
a change in the crystalline structure of tin
C.
an interaction with nitrogen of the air at very low temperature
D.
an interaction with water vapour contained in the humid air
Answer :
a change in the crystalline structure of tin
Solution :
$${\text{Grey tin}} \rightleftharpoons {\text{white tin }}$$
Grey tin is brittle and crumbles down to powder in very cold climate
The conversion of grey tin to white tin is acompained by increase in volume. This is known as tin plaque or tin disease.