3.
Mg = Mg2+ + 2 e-
K = K+ + e-
Cu = Cu2+ + 2 e-
Zn = Zn2+ + 2 e-
Fe = Fe2+ + 2 e-
Ag = Ag+ + e-

4.
K (kálium), Na (nátrium), lassan reagál: Mg (magnézium), csak az oxidréteg megbontása után reagál: Al (alumínium)

2 K + 2 H₂O = 2 KOH + H₂
2 Na + 2 H₂O = 2 NaOH + H₂
Mg + 2 H₂O = Mg(OH)₂ + H₂
2 Al + 6 H₂O = 2 Al(OH)₃ + 3 H₂

5.
alumínium
2 Al + 6 HCl = 2 AlCl₃ + 3 H₂

kálium
2 K + 2 H₂O = 2 KOH + H₂

Fe + Cu2+ = Fe2+ + Cu

alumínium
4 Al + 3 O₂ = 2 Al₂O₃

réz
Cu + 2 H₂SO₄ = CuSO₄ + SO₂ + 2 H₂O

A) nem reagál
B) 2 Ag + Hg2+ = 2 Ag+ + Hg
C) Cu + 2 Ag+ = Cu2+ + 2 Ag

6.
`color(red)("O")`XID
GÁ`color(red)("Z")`
KL`color(red)("Ó")`R
`color(red)("N")`EON
KRI`color(red)("P")`TON
H`color(red)("A")`T
`color(red)("J")`ÓD
S`color(red)("Z")`ÁZ
SÓ`color(red)("S")`AV

ÓZONPAJZS