Here's why:

* Polarity: Magnesium chloride is an ionic compound, meaning it's composed of positively charged magnesium ions (Mg²⁺) and negatively charged chloride ions (Cl⁻). This makes it highly polar. Hexane, on the other hand, is a nonpolar solvent.

* "Like dissolves like": The general rule of thumb is that polar substances dissolve in polar solvents, and nonpolar substances dissolve in nonpolar solvents. Since magnesium chloride is polar and hexane is nonpolar, they are not compatible.

In summary: Due to the significant difference in polarity, magnesium chloride will not dissolve in hexane.