Question

Which of the following is not a crystalline solid?
A) Common Salt
B) Sugar
C) Iron
D) Rubber

Answer 1

Solid is a substance which exists in solid state, it is one of the four fundamental states of matter. Solids are rigid. Solids do not change shape when force is applied on it. Solids have definite shape size and volume. There are two primary categories of solid that are amorphous and crystalline solids.

Complete answer:
Let us discuss the two types of solids.

Amorphous Solids: Solids which do not have long range order in the arrangement of their constituent particles in three dimensional spaces are known as amorphous solids. For example metallic glasses, lubricants etc.
Crystalline Solids: A crystal or a crystalline solid is a solid material whose constituent particles are arranged in highly ordered microscopic structure, forming a crystal lattice.
Solids which have long range order in the arrangement of their constituent particles in microscopic level are crystalline solids. For example Sodium chlorides, diamonds etc.
Now we have to discuss the given options and try to find out which one is not a crystalline solid.
As constituent particles of common salt are arranged in ordered structure and as it has crystal lattice so it is a crystalline solid.
As constituent particles of sugar are arranged in ordered structure and as it has crystal lattice so it is a crystalline solid.
As constituent particles of iron are arranged in ordered structure and as it has crystal lattice so it is a crystalline solid.
In case of rubber constituent particles are not arranged in a perfectly ordered manner so it is not a crystalline solid, as it is amorphous solid.

So the correct option is rubber that is (D).

Note: It is to be noted that if the constituent particles are not arranged in proper order then it is not a crystalline solid. Mostly metals and minerals are always crystalline in nature.