Question

Which characteristic could distinguish a crystalline solid from an amorphous solid?

Answer 1

Crystalline solids 
1. The internal arrangement of particles is well defined. The molecules are lined up in a very particular order. 
2. They possess sharp melting points. 
3. NaCl and NaF are examples of Crystalline solids. 

Amorphous solids 
1- The internal arrangement of particles is not well defined. Molecules are not in a particular arrangement. There is no regularity in their form.
2. They do not possess sharp melting points. 
3. Glass, rubber and plastics are examples of Amorphous solids..