Question

Methanides are:
A.$M{g_2}{C_3}$ ,$B{e_2}C$ ,$A{l_4}{S_3}$ and $Ca{C_2}$
B.$M{g_2}{C_3}$ ,$B{e_2}C$ and $A{l_4}{S_3}$
C.$B{e_2}C$, $A{l_4}{S_3}$ and $Ca{C_2}$
D.$B{e_2}C$ and $A{l_4}{S_3}$

Answer 1

We have to remember that the Methanides are a subset of carbides, they have a tendency to dissolve in water to produce methane. The methanides are having Carbon with C-4 oxidation state.

Complete step by step answer:
Let’s start with discussing a little about the methanides for better understanding of the question. Methanides are a subset of carbides, they have a tendency to dissolve in water to produce methane. Methanides exist in many forms and one of those forms is in the form of molecules with transition metals. But with transition metals the carbides usually dissolve very slowly in water which make them not so useful.
Coming back to the question we are given four compounds which are $M{g_2}{C_3}$ $B{e_2}C$ $A{l_4}{S_3}$ and $Ca{C_2}$. The methanides are having Carbon with C-4 oxidation state. Out of these $B{e_2}C$ and $A{l_4}{S_3}$ full-fill the condition of having C-4 ions in it. Hence the answer is $B{e_2}C$ and $A{l_4}{S_3}$.
So the answer to this question is option D. $B{e_2}C$ and $A{l_4}{S_3}$ .

Note:
We have to remember that the methane produced is used in the manufacturing of many organic chemicals. The methane is an odourless, colourless and flammable gas in nature. It is also used as a fuel for lighting purposes. Methane is also released from landfill, sewer, marshes and septic systems. As we know that the carbide of aluminium is known as aluminium carbide which looks like pale yellow to brown crystals. We must know that the Beryllium carbide is too hard like diamond which is prepared by heating beryllium with carbon at high temperature.