Element `X` forms a chloride with the formula `XCl_(2)`, 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) `Al` (d) `Si`

Explanation

Since element `X` forms a chloride `XCl_(2)` so the valency of `X` is 2. Now, out of `Na, Mg, Al` and `Si`, the element of valencey 2 is `Mg`, So `X` would be in the group as that of `Mg` (because all the elements of the same group have equal valency).