All the other halogens-chlorine, bromine and iodine- exhibit positive oxidation states upto +7, apart from the most stable negative state of -1. But fluorine is more electronegative than any other element in the periodic table and so it cannot be assigned a positive oxidation number in its compounds.

Positive and Negative Oxidation States

Oxidation state is a measure of the degree of oxidation of an atom in a chemical compound. It is represented by a numerical value that reflects the number of electrons an atom has gained or lost in the compound. Oxidation states can be positive, negative, or zero.

Elements can show multiple oxidation states depending on the chemical compound they are present in. Some elements show only one oxidation state, while others can show both positive and negative oxidation states.

Iodine as an Element

Iodine is a halogen element with atomic number 53. It is a non-metal and is found in group 17 of the periodic table. Iodine is a solid at room temperature and has a shiny metallic appearance. It is a highly reactive element and can form compounds with a wide range of oxidation states.

Iodine's Oxidation States

Iodine can exhibit both positive and negative oxidation states. It can have a maximum positive oxidation state of +7 and a minimum negative oxidation state of -1.

Some common compounds of iodine and their corresponding oxidation states are:

- Iodine pentoxide (IO5): Iodine exhibits a positive oxidation state of +5 in this compound.
- Iodine heptafluoride (IF7): Iodine exhibits a positive oxidation state of +7 in this compound.
- Potassium iodide (KI): Iodine exhibits a negative oxidation state of -1 in this compound.

Conclusion

Among the given options, only iodine shows both positive and negative oxidation states. Therefore, the correct answer is option C.