when water is combined with magnesium nitride to produce magnesium hydroxide and ammonia gas, is this reaction endothermic or exothermic and why?

Answer 1

Frankly, I don't know; however, you can calculate delta H from this.
Mg3N2 + 3H2O ==> 3MgO + 2NH3
Look up delta Hrxn = (n*delta H^o_f)_products - (n*delta H^o_f)_reactants