2C2H6 + 7O2 → 4CO2 + 6H2O
10 / 2 = X / 7
X = 10 × 7 / 2 = 45 л
45 л — 21%
Z л — 100%
Z = 45 × 100 / 21 = 214,28 л
Ba(OH)2 + MgCl2 = Mg(OH)2 + BaCl2
Ba(+2) + 2OH(-) + Mg(+2) + 2Cl(-) = Mg(OH)2 + Ba(+2) + 2Cl(-)
Mg(+2) + 2OH(-) = Mg(OH)2
Mg +12 -- 2, 8, 2
1s2 2s2 2p6 3s2
Ca +20 -- 2, 8, 8, 2
<span>1s2 2s2 2p6 3s2 3p6 4s2</span>
2)NaOH+HCl=NaCl+H2O
K2O+2HCl=2KCl+H2O
CuO+2HCl=CuCl2+H2O.