Statement I: II B group elements are represented as only d-block elements but not transition elements

Statement II: In transition elements n, (n −1) shells are incompletely filled

Statement I and statement II are true and statement II is correct explanation of statement I

The correct answer is option 1. Statement I and statement II are true and statement II is correct explanation of statement I

Statement I: II B group elements are represented as only d-block elements but not transition elements.

This statement is true because the II B group elements, which are Zn, Cd, and Hg, have completely filled d orbitals. This means that they do not exhibit the typical properties of transition elements, such as variable oxidation states and colored compounds.

Statement II: In transition elements n, (n −1) shells are incompletely filled.

This statement is also true. The d orbitals are part of the (n-1) shell, and in transition elements, these orbitals are only partially filled. This is what gives transition elements their characteristic properties.

The reason why statement II is the correct explanation for statement I is that the d orbitals are the ones that are responsible for the variable oxidation states and colored compounds of transition elements. If the d orbitals are completely filled, then the element cannot exhibit these properties.

For example, Zn has the electronic configuration [Ar]3d¹⁰4s². This means that the d orbitals are completely filled, and Zn can only have an oxidation state of +2. It cannot have other oxidation states, such as +1 or +3, because this would require the d orbitals to be partially filled.

In contrast, Fe has the electronic configuration [Ar]3d⁶4s². This means that the d orbitals are only partially filled, and Fe can have a variety of oxidation states, such as +2, +3, +4, and +6. This is because the d orbitals can accommodate more electrons, and the number of electrons in the d orbitals determines the oxidation state of Fe.

Therefore, statement II is the correct explanation for statement I. The d orbitals are the ones that are responsible for the variable oxidation states and colored compounds of transition elements, and if the d orbitals are completely filled, then the element cannot exhibit these properties.