Answer: The correct name for the compound 
is, Dicarbon triiodide.
Explanation:
is a covalent compound because in this compound the sharing of electrons takes place between carbon and iodine.. Both the elements are non-metals. Hence, it will form covalent bond.
The naming of covalent compound is given by:
The less electronegative element is written first.
The more electronegative element is written second. Then a suffix is added with it. The suffix added is '-ide'.
If atoms of an element is greater than 1, then prefixes are added which are 'mono' for 1 atom, 'di' for 2 atoms, 'tri' for 3 atoms and so on.
Hence, the correct name for the compound is, Dicarbon triiodide..
D:
When electrons are gained, the charge of the atom decreases.
When you are given an atom with a charge, the oxidation of that atom is the charge. So by going from a Cr^3+ (Oxidation Number = 3) to a Cr^2+ (Oxidation Number = 2), the Oxidation Number thus decreases.
Have a different number of protons
An atom is the smallest unit if a matter that has properties of an element.
A molecule is a single unit created by two or more atoms that are tightly bonded together.
Hope this helped :)
