Statement 1 : To obtain effective pπ−dπ overlap, the size of the d-orbital must be similar to the size of the p-orbital. So for chlorine pπ−dπ bonding is strongest in their oxoanions.Statement 2 : On moving a period from left to right in the periodic table, the nuclear charge is increased and more s and p-electrons are added. Since these s- and p-electrons shield the nuclear charge incompletely, the size of the atom and that of the d-orbitals decreases. This leads to progressively stronger pπ−dπ bonding.