According to VSEPR (Valence Shell Electron Pair Repulsion) theory, the shape of ICl4 (iodine tetrachloride) is described as square planar.
This molecular geometry arises because the iodine atom has four chlorine atoms attached to it and contains two lone pairs of electrons. In total, there are six electron pairs (four bonding pairs and two lone pairs) surrounding the central iodine atom. VSEPR theory states that these electron pairs repel each other and will arrange themselves to minimize repulsion.
In the case of ICl4, the two lone pairs occupy positions opposite each other in order to maximize their distance from the bonding pairs. This results in the four chlorine atoms forming a square around the iodine atom, leading to a square planar shape.
Therefore, the correct answer is b) square planar.