Select incorrect statement(S).
A. Interstitial carbides are formed by metalloids like ${{Si}}$ and ${{B}}$.
B. Covalent carbides are formed by metalloids.
C. ${{CO}}$ and ${{C}}{{{N}}^{{ - }}}$ both are fatal due to complex formation with ${{Fe}}\left( {{{{\rm I}{\rm I}{\rm I}}}} \right)$ present in blood.
D. ${{SiC}}$ is called carborundum.

Hint: Interstitial carbides are mainly derived from the transition metals which act as host lattice for small carbon atoms which occupies the interstices of the metal atoms. Carbides are mainly composed of carbon and a less electronegative element.

Complete step by step answer:
Metalloids are materials that have properties that could belong to either metals or non-metals
The compounds that are formed when small atoms like ${{H, C \;or\; N}}$ are trapped inside the crystal lattices of metals are called Interstitial compounds. They are usually non stoichiometric and are neither typically covalent or ionic.
Interstitial carbides are primarily derived as large transition metals that act as host lattice for small carbon atoms that occupy the interstices of the metal atoms that are closely packed. Thus the Interstitial carbides are formed only by ${{Si}}$ and the first statement is incorrect. Metalloids like ${{B}}$ and ${{Si}}$ forms carbides and covalent bond exists between the carbon atom and metalloid atom (either ${{B}}$ or ${{Si}}$). Carborundum is a black solid having silicon carbide (${{SiC}}$) which can be used as an abrasive and ${{CO}}$ and ${{C}}{{{N}}^{{ - }}}$ both are fatal due to complex formation with ${{Fe}}\left( {{{{\rm I}{\rm I}{\rm I}}}} \right)$ present in blood.

So, the correct answer is Option A.

Additional information:
Properties of metalloids
They are generally solids like metals, and brittle like non- metals
Their ability to conduct heat is in between metals and non- metals
They conduct electricity at a higher temperature
The metalloids that are able to conduct electricity at high temperatures are called semiconductors. Thus ${{Si}}$ which is a metalloid that conduct electricity and could be used in electronic devices, metalloids other than ${{Si}}$ are Boron, Germanium, Arsenic, Antimony and Tellurium.

Note: Interstitial carbides are characterised based on their extreme brittleness and its extreme hardness, they have got a high melting point. In some cases they exhibit catalytic, magnetic properties and also superconductivity.