In this system, we have magnesium (Mg), magnesium chloride (MgCl2), magnesium hydroxide (Mg(OH)2) and copper hydroxide (Cu(OH)2) present.

Possible reactions that can occur in this system are:

Mg + 2HCl -> MgCl2 + H2 (acid-base reaction)MgCl2 + 2NaOH -> Mg(OH)2 + 2NaCl (double displacement reaction)Cu(OH)2 -> CuO + H2O (decomposition reaction)

The exact reactions that will take place depend on the concentrations of the substances and the conditions of the system.