When 1.0 mole of MgSO4 is dissolved in water contained in a calorimeter, the temperature of the water and dissolved ions increases. Therefore the sign of AH for this reaction is heat is transferred the system the surroundings, and the reaction is classified as +, from, to, exothermic
-, from, to, endothermic
+, from, to, endothermic
-, to, from, endothermic
-, from, to, exothermic
-, to, from, exothermic

-, from, to, exothermic

Explanation:

When 1.0 mole of MgSO₄ is dissolved in water contained in a calorimeter, the temperature of the water and dissolved ions increases.

Therefore the sign of ΔH for this reaction is "-". By convention, for exothermic reactions, the enthalpy has a negative sign.

Heat is transferred from the system to the surroundings. This heat, released by the system, is absorbed by the surroundings and used to raise their temperature.

The reaction is classified as exothermic.