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.

Solution

Chemistry ma’am · 3 steps

Crystals are ordered all through, amorphous solids only locally: test each statement on that.

1. Crystalline solids. Their particles repeat in a regular pattern through the whole crystal, so they have long range order. That pattern looks different along different directions, so properties like refractive index and conductivity change with direction. That makes them anisotropic, not isotropic.
2. Amorphous solids. Their particles are ordered only over short distances, like in a liquid. So they are called pseudo solids or supercooled liquids. Different parts need different energies to break apart, so they soften gradually over a range of temperatures and have no definite heat of fusion.

   Statement	True or false	Reason
   (A) Long range order in crystals	True	Regular pattern repeats throughout
   (B) Crystals are isotropic	False	Crystals are anisotropic
   (C) Amorphous solids are pseudo solids	True	Only short range order, like liquids
   (D) Amorphous solids soften over a range	True	No sharp melting point
   (E) Amorphous solids have a definite heat of fusion	False	Only crystals have a definite heat of fusion

3. So. The correct statements are (A), (C) and (D), which is option (d).

The idea to keep. Crystalline means long range order, sharp melting point, definite heat of fusion and anisotropy. Amorphous is the opposite on every point: short range order, a softening range and isotropy.

Answer from the NTA final answer key. Solution by PrepWiser.