Write a short summary of the text in ex. 138 on page 91. Firstly, I’d like to say that... Secondly, I know that smoking...

1) Zn+NiCl2= ZnCl2+ Ni
2) 2Ca+ O2= 2CaO( обычные условия) 
3) 2Na+ S= Na2S
4) Mg+ H2SO4= MgSO4+ H2
5) Ca+ 2H2O= Ca(OH)2 + H2( газ) 
6) Ni+Co( NO3)2= Ni(NO3)2+ Co