Here's why:

* Solubility Rules: Solubility rules are a set of guidelines used to predict whether a compound will dissolve in water.

* Chlorides: Most chlorides are soluble, with the notable exceptions of silver chloride (AgCl), lead(II) chloride (PbCl₂), and mercury(I) chloride (Hg₂Cl₂).

* Manganese(II): Manganese(II) is not one of the exceptions to the rule for chloride solubility.

Therefore, manganese(II) chloride (MnCl₂) is soluble in water.