Question

MgO - X - Mg(OH)2 - MgO - Mg(NO3)2 - NaNO3​

Answer 1

MgO + H2O -> Mg(OH)2
Mg(OH)2 -> MgO + H2O
MgO + 2HNO3 -> Mg(NO3)2 + H2O
Mg(NO3)2 + 2NaOH -> 2NaNO3 + Mg(OH)2