Element X forms a chloride with the formula XCl2, which is a solid with a high melting point. X would most likely be in the same group of the Periodic Table as (a) Na (b) Mg (c) AI (d) Si

The answer is Magnesium (Mg), It has a valency of 2, which is the same as the group (a) Na (b) Mg (c) AI (d) Si

Also, Mg, when combined with chloride, forms Magnesium Chloride ( MgCl₂).