Which of the following is an ionic solid?

What type of solid is silica?

Amorphous substances show:

Which of the following characteristic properties is $NOT$ true for crystalline solids?

Soldiers of Napoleon's army while at the Alps during a freezing winter suffered a serious problem regarding the tin buttons of their uniforms. White metallic tin buttons got converted to grey powder. This transformation is related to

Write a note on metallic solids.