Redox reaction

What is the oxidation number of iodine in KI3?

• -1

• 0

• +1

• +5

What is the oxidation number of Fe in Fe3O4?

• +4 and +5

• +3 and +4

• +2 and +3

• +1 and +2

What is the oxidation number of each terminal S atom in tetrathionate (H₂S406)?

• +5

• +4

• +3

• +2

What is the oxidation number of C in CH3CH₂OH or C₂H₂O?

• -2

• -1

• -3

• -4

How many hydrogen atoms is the second carbon attached to in CH3CH₂OH?

• 4

• 3

• 2

• 1