Question

Write an overall equation for the acid-base reaction that would be required to produce the following salt.MgCl2

Answer 1

You need a base containing calcium and the acid must be sulphuric acid
This could be done using calcium hydroxide and sulphuric acid.
Te equation is:
Ca(OH)2(aq) + H2SO4(aq) → CaSO4(s) + 2H2O(l)
I have gone this route because you specifically ask for an acid/ base reaction.
There are some practical problems with the above:
Ca(OH)2 is only sparingly soluble in water. The insoluble CaSO4 produced tends to interfere with the ongoing reaction between the Ca(OH)2 and the H2SO4
This is even more pronounced if you use CaCO3 as the starting base. The reaction hardly proceeds at all due to the CaSO4 masking the CaCO3

If I wished to produce CaSO4 with a free choice of reactants I would go this route:
CaCl2(aq) + Na2SO4(aq) → CaSO4(s) + 2NaCl.
This reaction would go to completion without any problem

Answer 2

Ca(OH)2 + H2SO4 --> CaSO4 + 2H2O hope this helps