What is the formula for Iodine Pentafluride?

It's IF5.

1. In each compound given, there are two different elements involved. What you see there are what you call binary compounds. Binary compounds are compounds formed by two different elements.

2. The elements involved are all non-metals. This is why they form covalent compounds and gives reason as to how they are named as well.

3. The reason why we cannot use carbon monoxide on both is because:

CO only has 1 carbon atom and 1 oxygen atom, while CO₂ has 1 carbon and 2 oxygen atoms. (Which by way you made a mistake in). Since there are 2 oxygen atoms on the second compound, you need to use the prefix "di" to indicate that there are 2.

4. The pattern in naming these compounds is that the name depends on how many atoms there are of each element.

Let's take the first CO and compare it to N₂O₅ .

CO

There is only 1 atom of carbon and 1 atom of oxygen.

The first element is named as is, if there it only has 1 atom.

Carbon

The second element though, the prefix is always put:

Carbon monoxide.

N₂O₅ on the other hand has 2 nitrogen atoms and 5 oxygen atoms.

Because there is more than one nitrogen, you need to put the prefix as well:

Dinitrogen

And the second element has 5 atoms of oxygen

Dinitrogen pentoxide.