<span>а)<u><em><span>Zn</span></em></u>+О2=ZnO,</span>
<span>б)<u><em>Ca</em></u>+ O2=CaО</span>
<span>в)<u><em>Cr</em></u>+O2=Cr2O3</span>
CaCO3=CaO+CO2
m(CaCO3)=12г*0,9=10,8г
M(CaCO3)=100г/моль
n(CaCO3)=10.8/100=1.08 моль=n(CO2)
V(CO2)=22.4*1.08=24.192 л
<span>2H2O + 2Na = 2NaOH + H<span>2
</span></span><span>NaOH + CO2 = NaHCO<span>3
</span></span><span>NaHCO3 + NaOH = Na2CO3 + H2O
</span>
<span>FeCl2 + 2NaOH = Fe(OH)2 + 2NaCl
</span><span>Fe(OH)2 + Na2SO4 = FeSO4 + 2NaOH
</span>2Al + 3FeSO4 = Al2(SO4)3 + 3Fe
<span>4P + 5O2 = P4O<span>10
</span></span><span>12HNO3 + P4O10 = 4H3PO4 + 6N2O<span>5
</span></span><span>3NaOH + H3PO4 = Na3PO4 + 3H2O
2Na3PO4 + 3CaCl2 = Ca3(PO4)2 + 6NaCl
</span>
Вот все решения наглядно написал в картинках: