Electron Transfer Theory

Question

Write an label the oxidation and reduction half-reaction equations.
a) Ni(s) + Cu(NO3)2(aq) -> Cu(s)+ Ni(No3)2(aq)
oxidation - Ni(s) -> Ni2+(aq) + 2e-
reduction - Cu2+(aq) + 2e- -> Cu(s)

b) Pb(s) + Cu(NO3)2(aq) -> Cu(s) + Pb(NO3)2(aq)
oxidation - Pb(s) -> Pb2+(aq) + 2e-
reduction - Cu2+(aq) +2e -> Cu(s)

c) Ca(s) + 2HNO3(aq) -> H2(g) + Ca(NO3)2(aq)
oxidation - Ca(s) -> Ca2+(aq) + 2e-
reduction - 2H+(aq) + 2e- -> H2(g)

d) 2Al(g)+ Fe2O3(s) -> 2Fe(l) + Al2O3(s)
oxidation - 2Al ->

I have no idea what to do with the last one. If I made any mistakes or did anything wrong can someone correct them.

Oxidation Numbers
Assign oxidation numbers to chloride in each of the follow chemicals.
HCl = +1?
Cl2 = 0?
NaClO = ?
Cl- = -1?
HClO3 = either +1 or -3?
ClO3- = -3?
KClO2 - +2?
ClO2 = +2?
HClO4 = +4?

I have no idea if I'm doing these right. Can someone explain oxidation numbers and correct those?

Also can someone do an example in this and explain how they got it. I don't understand the concept.

Assign oxidation numbers to manganese in each of the following chemicals.
MnO4^2-(aq)

Use oxidation numbers to identify the oxidation and reduction atoms
MnO4-(aq) + H2Se(g) + H+(aq) -> Se(s) + Mn2+(aq) + H2O(l)

Can someone please do those examples and explain how they got the answers because I don't understand oxidation numbers.

Answer 1

Answered above.

Answer 2

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Answer 3

what occurs during the operation of a voltaic cell based on the following reaction?..... Ni (s) + Pb2+ (aq) --> Ni2+ (aq) + Pb (s)