Answer:
Explanation:
a) 
Oxidation state of Mg changes to 0 to +2.
Oxidation state of Ni changes to +2 to 0.
Oxidation state of Cl does not change.
So, Mg is oxidized, Ni is reduced.
Mg acts as reducing agent and
acts as oxidizing agent.
b) 
Oxidation state of P changes to +3 to +5.
Oxidation state of Cl changes to 0 to -1.
So,
P is oxidized and Cl is reduced.
acts as reducing agent and
acts as oxidizing agent.
c) 
Oxidation state of C changes to -2 to +4.
Oxidation state of O changes to 0 to -2.
Oxidation state of H does not change.
So,
C is oxidized and O is reduced.
acts as reducing agent and
acts as oxidizing agent.
d) 
Oxidation state of Zn changes to 0 to +2.
Oxidation state of H changes to +1 to 0.
Oxidation state of S and O do not change.
So, Zn is oxidized, H is reduced.
Zn acts as reducing agent and
acts as oxidizing agent
e) 
Oxidation state of S changes to +2 to +2.5.
Oxidation state of I changes to 0 to -1.
Oxidation state of K and O do not change.
So, S is oxidized, I is reduced.
acts as reducing agent and
acts as oxidizing agent.
f) 
Oxidation state of Cu changes to 0 to +2.
Oxidation state of N changes to N +5 to +2.
Oxidation state of H and O do not change.
So, Cu is oxidized, N is reduced.
Cu acts as reducing agent and
acts as oxidizing agent