The reason why solid $NaCl$ is a poor conductor of electricity is .......

Choose the correct option for crystalline solids based on the following statements:
$(1)$ They do not have a sharp melting point.
$(2)$ They gradually soften upon heating.
$(3)$ They have an irregular three-dimensional arrangement.
$(4)$ They show a rapid change in volume upon heating.

Low melting point is expected for a solid of which type?

Which among the following is an example of an amorphous solid?

Which of the following statements is $NOT$ true about polymorphism?

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