Select the correct statements for the d-block and f-block elements:

A. The maximum oxidation state shown by manganese is +6.

B. \(Sc^{3+}\) (Scandium) is colourless

C. Brass is an alloy of Copper and Zinc

D. Lanthanide series included a total of 15 elements

E. \(V_2O_5\) (Vanadium Pentaoxide) is used in the manufacturing of sulphuric acid (by contact process).

Choose the correct answer from the options given below:

B, C and E only

The correct answer is option 3: B, C and E only.

Let us analyze each statement:

A. The maximum oxidation state shown by manganese is +6: This is incorrect. Manganese's highest oxidation state is +7, achieved in compounds like KMnO₄ (potassium permanganate).

B. Sc³⁺ (Scandium) is colourless: This is correct. Sc³⁺ has no unpaired electrons in its d orbitals, resulting in no d-d electron transitions and a colourless ion.

C. Brass is an alloy of Copper and Zinc: This is correct. Brass is a widely used alloy with a composition of roughly 70% copper and 30% zinc.

D. Lanthanide series included a total of 15 elements: This is incorrect. The lanthanide series consists of 15 elements, starting from Lanthanum (La) to Lutetium (Lu).

E. V₂O₅ (Vanadium Pentaoxide) is used in the manufacturing of sulphuric acid (by contact process): This is correct. V₂O₅ acts as a catalyst in the contact process for sulphuric acid production by converting SO₂ to SO₃.

Therefore, only statements B, C, and E are true, making option (3) the correct answer.