2) consider the reaction h2s + i2 → 2hi + s
a) name the substance oxidized
b) name the substance reduced
c) name the oxidizing agent
d) name the reducing agent

The oxidizing agent is the one that is reduced which is also the one who gains electron. The reducing agent is the one that is oxidized which is also the one who loses electron. Thus,

a. The substance H2S is the one oxidized.
b. The substance I2 is the one reduced.
c. The oxidizing agent is I2.
d. The reducing agent is H2S.

D)can be increased in a closed system