Question

A solid crystal in which a face on one side is opposite to a point on the other, is called:

• A. Enantiomorphous
• B. Centrosymmetric
• C. Non-centrosymmetric
• D. Hemimorphic

Hint:

Hemimorphic crystals have dissimilar opposite ends.

Answer 1

The Correct Option is D

Concept:
In crystallography, symmetry of a crystal is identified by the arrangement of faces, edges, points and symmetry elements.

Step 1: Understand the given condition.
The question says that a face on one side of the crystal is opposite to a point on the other side. This means the two ends of the crystal are not similar.

Step 2: Identify the crystal character.
When the opposite ends of a crystal are dissimilar, the crystal is called hemimorphic. \[ \text{Face on one side and point on opposite side} \Rightarrow \text{Hemimorphic} \]

Step 3: Eliminate other options.
Centrosymmetric crystals have a centre of symmetry.
Enantiomorphous crystals are mirror-related forms.
Non-centrosymmetric is a broad term, but the specific term for this condition is hemimorphic. \[ \therefore \text{Correct Answer is (D)} \]