Question

Which one is not the property of crystalline solid?
A. A definite and regular geometry.
B. High intermolecular forces.
C. Isotropic.
D. Sharp melting point.

Answer 1

Hint:
We know that crystalline solids are solids that have closely packed atoms and molecules. They are harder than amorphous solid and have a definite pattern. They show anisotropy and give more properties of solid than that by amorphous solids.

Complete step by step solution
Crystalline solids are said to be anisotropic, because they show anisotropic behavior. A substance is said to be anisotropic in nature, if the value of physical properties such as refractive index, electrical conductivity, bond dissociation energy is different in different directions. This arrangement leads to the anisotropy of the crystals, which means their certain properties, such as electrical conductivity, optical properties and young’s modulus, are directionally dependent, which is different from glass and polycrystals.

Crystalline solids possess a distinctive internal structure by which they can change the distinctive flat surface or faces. That angle when the faces intersect, are the characteristic of substances. When X-rays are projected, it can help to identify the material by producing a distinctive pattern. We cannot say that this angle is dependent on the size of the crystal because the component, atom or ion have different arrangements so they reflect the same arrangement.

Therefore, the correct answer is C.

Notes:
Crystals also have very well defined melting points because the regularity of the atomic structure means that an atom exists in an identical local environment. Thus, the intermolecular forces acting on each atom are identical which makes the thermal energy required to break those forces identical throughout the solid, so it will melt simultaneously.