Answer:
Part 1.
There is no attachment for reaction:
But Option D will be correct because in two half reactions a single compound cannot both oxidized or reduced. Hence it may be oxidized in I and reduced in II .
Part 2.
In a reduction reaction, the oxidation number becomes more negative due to gain of electrons. Option B is correct.
Step-by-step explanation:
The oxidation number of simple ions is equal to the charge on the ion. So more negative means more electrons are added.
Part 3:
The half-reaction 2MnO2 + H2O + 2e- Mn2O3 is missing OH- ions.
Step-by-step explanation:
The full equation is :
2MnO2 + H2O + 2e- → Mn2O3 + 2OH-
So OH- ion were also produced.
Part 4:
The oxidation number of S in SO2 is +4.
For SO2-1 = +3
For SO2-2 = +2
For SO2-4 = +1
Rule 5 says that the sum of oxidation numbers for neutral compounds must be 0.
In charged compounds equal to net charge.