Hbr + h₂so₄ so₂ + br₂ + h₂o
what is the oxidation number of the oxidizing agent?
what is the oxidation number of the reducing agent?

The reaction equation is:
HBr + H₂SO₄ → SO₂ + Br₂ + H₂O

An oxidizing agent is a substance that itself becomes reduced and oxidizes the other chemical species in the reaction mixture. A reducing agent is similar, except that it becomes oxidized and reduces the other substance. 
In the reaction, the valency of bromine changes from -1 to 0, so it is oxidized, making it the reducing agent. The valency of sulfur changes from +6 to +4, so it is reduced, making it the oxidizing agent.

13) a 14) a15) b16) i don't know sorry17) a (maybe)

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