Which of the following is characteristic property of interstitial compounds?
A. Interstitial compounds are formed when small atoms like H, C or N are trapped inside the crystal lattices of metals.
B. Interstitial compounds are very reactive.
C. They typically show covalent character and are generally soft.
D. They retain metallic conductivity.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A and D only
Interstitial compounds form when small atoms such as H, C or N are trapped in the empty spaces of a metal lattice (TiC, \( \ce{Mn4N} \), \( \ce{Fe3H} \)).
A. Interstitial compounds are formed when small atoms like H, C or N are trapped inside the crystal lattices of metals. — Correct. This is the definition of an interstitial compound.
B. Interstitial compounds are very reactive. — Incorrect. They are chemically inert.
C. They typically show covalent character and are generally soft. — Incorrect. They are neither typically covalent nor ionic, and they are very hard, not soft.
D. They retain metallic conductivity. — Correct. The metal lattice stays intact, so they still conduct electricity like the metal.
NCERT (2026-27 edition):
Formation of Interstitial Compounds
