Question

Magnesium carbide is known as allylide as it produces allylene (propyne) on hydrolysis.

Answer 1

Hint: Commercially alkynes like ethylene and propylene as produced from metal carbide by the action of water on it. The metal carbides belong to the second group of the S-block.

Complete answer:
> Carbides are those compounds in which the metal is attached to the carbon atom. Magnesium that is an element of group 2 of the s-block also forms a compound with carbon known as magnesium carbide. Its formula is $M{{g}_{2}}{{C}_{3}}$ and its molecular weight is 84.64 g/mol. It is a silver-grey solid that has many shapes like discs, rod, Pelle, etc. and it is insoluble in water.
> Magnesium carbide is used for the preparation of alkyne or specifically propyne by the action of water. Alkynes are those compounds in which there is a triple bond present between two carbon atoms. Commercially alkynes like ethylene and propylene as produced from metal carbide by the action of water on it. So the magnesium carbide is known as allylide and allylic are those carbides that can give alkynes.
So, when one mole of magnesium carbide reacts with four moles of water, it forms one mole of propyne and two moles of magnesium hydroxide. 

The reaction is given below:
$M{{g}_{2}}{{C}_{3}}+4{{H}_{2}}O\to C{{H}_{3}}-C\equiv CH+2Mg{{(OH)}_{2}}$
This reaction can also be used in the laboratory of making the propyne. It produces propene because there are 3 carbon atoms in the magnesium carbide molecule.

Note: Another carbide that can be used to produce an alkyne is calcium carbide because when calcium carbide reacts with water it produces acetylene or ethyne and calcium hydroxide. 

The reaction is given below:
$Ca{{C}_{2}}+2{{H}_{2}}O\to CH\equiv CH+Ca{{(OH)}_{2}}$