# Formation of interstitial compounds makes the transition metal more:

(A) Soft $\quad$ (B) Ductile $\quad$ (C) Hard $\quad$ (D) Metallic

Most transition metals form interstitial compounds with small non metal atoms such as H, Bo, C and N.
These small atoms enter the voids between packed atoms of crystalline transition metals.
They form chemical bonds with them, for example, steel and iron becomes harder by forming interstitial compounds with Carbon.
edited Aug 6, 2014