Q. When NH4NO3 is dissolved in water, the temperature of the water decreases.  When NaOH is dissolved in a separate water sample, the temperature of the water increases.  Based on these observations, it can be concluded that the dissolving of?

1. NH4NO3 is endothermic and the dissolving of NaOH is exothermic.
2. both salts are exothermic
3. NH4NO3 is exothermic and the dissolving of NaOH is endothermic
4. both salts are endothermic