The incorrect statement among the following regarding crystalline solid is -

1. Definite and characteristic heat of fusion.
2. Isotropic nature.
3. A regular periodically repeated pattern of arrangement of constituent particles in the entire crystal.
4. A true solid.

HINT: Crystalline solids consist of atoms, ions, and molecules arranged in a strongly ordered microscopic arrangement.
Explanation:
Crystalline solids are anisotropic in nature as this solid shows different physical properties such as electrical resistance, the refractive index in different directions.

Property

Types of solid

Physical properties

Isotropy 

Anisotropy 

Amorphous solid

Crystalline solid

Same value

Different values


So, option 2 is the correct answer.