You're asking about a binary compound made from iodine (I) and chlorine (Cl). To determine the ratio of iodine atoms to chlorine atoms, we need to consider the possible valencies (combining power) of these elements.

* Iodine (I) typically has a valence of -1, meaning it gains one electron to achieve a stable octet.

* Chlorine (Cl) also typically has a valence of -1, meaning it gains one electron to achieve a stable octet.

Since both elements have the same valency, they will combine in a 1:1 ratio to form a neutral compound. This means there will be one iodine atom for every one chlorine atom.

The formula for this compound is ICl (iodine monochloride).