urgent dau coroana!!
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Răspuns:
Explicație:
1.
a.
2HCl + Na2O=2 NaCl + H2O
b.
CaCO3= CaO + CO2
c.
2Na+ Cl2= 2NaCl REACTIE DE COMBINARE
d.
Na2O + H2O= 2NaOH REACT. DE COMBINARE
2.
a. 2Mg + O2 =2 MgO REACTIE DE COMBINARE
b. 2 Ca + O2 =2 CaO REACT. DE COMBINARE