What elements form chlorides with formula xcl?

Since chlorine favours a (-1) oxidation state, it forms an ionic bond with group one metals with the formula XCl. All group one metals react vigorously with chlorine gas; and each reaction gets more violent as you move down Group 1 and produces a white crystalline salt. The reaction with chlorine is as follows 2X + Cl2 which gives 2XCl. Where X is an Alkali metal.

It has to be b i hope this

The activity series is shown in the attached picture. if the element is below the other, then you can displace the other. following the activity series as a guide, the reactions are as follows: nickel and aluminum chloride3 ni + 2 alcl₃  → 3 nicl₂ + 2 albarium and copper bromideba + cubr  →  no reaction because cu is less oxidizable than bapotassium nitrate and aluminum3 kno₃ + al  → al(no₃)₃ + 3 ksodium phosphate and zincnaso₄ + zn  → znso₄ + na