Question

Select ionic carbides.
A. $\text{A}{{\text{l}}_{\text{4}}}{{\text{C}}_{\text{3}}}\text{, Ca}{{\text{C}}_{\text{2}}}\text{, M}{{\text{g}}_{\text{2}}}{{\text{C}}_{\text{3}}}$
B. $\text{A}{{\text{l}}_{\text{4}}}{{\text{C}}_{\text{3}}}\text{,SiC,}{{\text{B}}_{\text{4}}}$
C. $\text{Ca}{{\text{C}}_{\text{2}}}\text{, M}{{\text{g}}_{\text{2}}}\text{, }{{\text{C}}_{\text{3}}}$
D. $\text{Ca}{{\text{C}}_{\text{2}}}\text{, M}{{\text{g}}_{\text{2}}}\text{, SiC, M}{{\text{g}}_{\text{2}}}{{\text{C}}_{\text{3}}}$

Answer 1

Hint: In chemistry, as we know that a carbide usually describes a compound composed of carbon and a metal. The various classifications of carbides are: ionic carbides or salt, covalent compounds, interstitial compounds, intermediate transition metal carbides. On the basis of the fact whether they are electronegative or electropositive we can classify them as ionic or not.

Complete step-by-step answer:
Carbide is a compound of carbon with less electronegative element. The most electropositive metals form ionic carbides.
Examples: $\text{A}{{\text{l}}_{\text{4}}}{{\text{C}}_{\text{3}}}$,$\text{CaC}{{\text{l}}_{\text{2}}}$, $\text{M}{{\text{g}}_{\text{2}}}{{\text{C}}_{\text{3}}}$.

Non-metals of electronegativity similar to that of carbon form covalent carbides.
Examples: $\text{SiC}$, ${{\text{B}}_{\text{4}}}\text{C}$
Therefore, the correct option of the ionic carbides is Option A.

Additional Information:
Interstitial carbides are derived primarily from relatively large transition metals that act as a host lattice for the small carbon atoms, which occupy the interstices of the close packed metal atoms.
There are only two compounds which are considered completely covalent carbides, the form of the two elements are similar to carbon in size and electronegativity. The compounds are Boron and Silicon.
In intermediate transition metal carbides, the transition metal ions are smaller than the critical 135 pm and the structures are not interstitial but are more complex.
Carbides for a long time has been used as an abrasive substance, which is used in the manufacture of sand papers, grinding wheels and cutting tools in industry. It is also used in heating elements in furnaces and refractory lining.

Note: We know that ionic carbides have discrete carbon anions of the forms ${{\text{C}}^{\text{4}-}}$. Sometimes they are also called methanides, since they can be viewed as being derived from methane.