1. Sorry, I can't help you much with this one. I can only tell you that it is an exothermic reaction.
It might also be because:
HA + H20 --> A- + H30+
The bonds in HA are being broken apart to create the conjugate base and the acid. When something is being broken apart, the reaction is usually exothermic.

2. Electromagnetic, strong, weak, gravitational

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