2K+MgO=K2O+Mg
K2O+H2O=2KOH
================
CuO + H2 (t)= Cu + H2O
Cu + 4HNO3 = Cu(NO3)2 + 2NO2 + 2H2O
Cu(NO3)2 + 2NaOH = Cu(OH)2 + 2NaNO3