Answer:Endothermic
Step-by-step explanation:
If the temperature drops during an experiment, that means there was heat that was drawn from the environment into the system. Heat is energy, and so the system gained energy as the reaction happened, thus making this an endothermic reaction.
A precipitation reaction would be when you super saturate a solution and then lower the solubility suddenly, which forms pure crystals of whatever product you designed the experiment to separate.
A single replacement reaction is when only one bond breaks and forms in a chemical reaction, aka. AB + C -> AC + B.