Select the correct statements.
(A) Crystalline solids have long range order.
(B) Crystalline solids are isotropic.
(C) Amorphous solid are sometimes called pseudo solids.
(D) Amorphous solids soften over a range of temperatures.
(E) Amorphous solids have a definite heat of fusion.
Choose the most appropriate answer from the options given below.

First, let us recall the fundamental characteristics of the two broad classes of solids studied in chemistry, namely crystalline solids and amorphous solids.

A crystalline solid possesses a regular three-dimensional arrangement of constituent particles (atoms, ions or molecules). Because this arrangement repeats in space, we say the solid exhibits long-range order. Hence statement (A) “Crystalline solids have long range order” is correct.

Next, we look at the directional dependence of physical properties. If a property such as refractive index, thermal conductivity or electrical resistance has the same magnitude in every direction, the solid is termed isotropic. Owing to their orderly yet direction-specific arrangement, crystalline solids generally show different values of these properties along different crystallographic directions; therefore crystalline solids are not isotropic but anisotropic. Statement (B) “Crystalline solids are isotropic” is thus incorrect.

An amorphous solid, in contrast, lacks long-range order; only short-range order is present. Because of this disordered, glass-like nature, such solids behave like super-cooled liquids and are sometimes referred to as pseudo solids or super-cooled liquids. Therefore statement (C) “Amorphous solids are sometimes called pseudo solids” is correct.

Furthermore, when heat is supplied, a crystalline solid melts sharply at one definite temperature: it has a fixed, well-defined melting point and hence a definite heat of fusion. An amorphous solid, however, does not melt abruptly; instead it gradually softens over a broad temperature interval, passing through a viscous stage before becoming a liquid. Hence statement (D) “Amorphous solids soften over a range of temperatures” is correct, while statement (E) “Amorphous solids have a definite heat of fusion” is incorrect because a definite heat of fusion is characteristic of crystalline, not amorphous, solids.

Collecting the results, the correct statements are (A), (C) and (D). These correspond to Option D in the list provided.

Hence, the correct answer is Option D.