Match List I with List II

Choose the correct answer from the options given below:

A-III, B-I, C-IV, D-II

The correct answer is option 3. A-III, B-I, C-IV, D-II.

Let us explore each statement in detail to understand why the correct matching is:

A. Transition metal that doesn't show variable oxidation state: III. Scandium (Sc):

Scandium typically exhibits only one oxidation state in its compounds, which is \(+3\). This is due to the fact that it loses its three valence electrons (two 4s and one 3d) to form \(Sc^{3+}\).

Variable Oxidation States: Unlike many transition metals, which can exhibit multiple oxidation states, scandium does not. It does not show variable oxidation states, making it unique in this respect.

2. Metal of 3d-series that exhibits maximum number of oxidation states : (I) Manganese (Mn): Manganese is notable for its ability to exhibit a wide range of oxidation states, from \(+2\) to \(+7\). This is due to the relatively high number of electrons in its 3d and 4s orbitals, which allows for a variety of oxidation states.

Examples: For instance, in \(MnO_4^-\) (permanganate), manganese has an oxidation state of \(+7\), whereas in \(Mn^{2+}\), it has an oxidation state of \(+2\). This extensive range is the widest among the 3d-series elements.

3. Transition metal with positive \(M^{2+}/M\) value : (IV) Copper (Cu):

Positive \(M^{2+}/M\) Value: Copper has a positive \(M^{2+}/M\) value because it readily forms \(Cu^{2+}\) ions. The \(Cu^{2+}\) state is quite stable, and this characteristic is highlighted in reactions and electrochemical series.

Example: Copper(II) sulfate (\(CuSO_4\)) is a common example where copper is in the \(+2\) oxidation state.

4. Element of 3d-series which is colorless in its compounds : (II) Zinc (Zn):

Colorless Compounds: Zinc compounds are generally colorless because the \(Zn^{2+}\) ion has a completely filled 3d orbital (d^10 configuration), which does not absorb visible light. Thus, zinc compounds, like zinc sulfate (\(ZnSO_4\)) or zinc chloride (\(ZnCl_2\)), are colorless.

Contrast with Other 3d Elements: Other transition metals often form colored compounds due to partially filled d-orbitals, which can absorb certain wavelengths of visible light.

So, the correct matches are: 3. A-III, B-I, C-IV, D-II.