The molarity of a solution is defined as the number of moles of solute per liter of solution. In this case, we have 4.9 moles of MgCl in 4.3 liters of solution. Therefore, the molarity of the solution is:

$$Molarity = \frac{moles \ of \ solute}{liters \ of \ solution}$$

$$Molarity = \frac{4.9 \ moles}{4.3 \ liters}$$

$$Molarity = 1.14 M$$

Therefore, the molarity of the solution is 1.14 M.