Answer
a) Na is the reducing agent. Cl$_{2}$ is the oxidizing agent.
b) N in HNO$_{3}$ is the oxidizing agent. I in HI is the reducing agent.
c) N in HNO$_{3}$ is the oxidizing agent. S in H$_{2}$S is the reducing agent.
d) Pb in PbSO$_{4}$ is the oxidizing-reducing agent.
Work Step by Step
a) Na is the reducing agent. Cl$_{2}$ is the oxidizing agent.
b) N in HNO$_{3}$ is the oxidizing agent. I in HI is the reducing agent.
c) N in HNO$_{3}$ is the oxidizing agent. S in H$_{2}$S is the reducing agent.
d) Pb in PbSO$_{4}$ is the oxidizing-reducing agent.
