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:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → B, C and E only
A. The maximum oxidation state shown by manganese is +6. — Incorrect. Mn (Z = 25, [Ar]3d54s2) can use all seven 3d and 4s electrons; it shows +7 in \( \ce{KMnO4} \) and \( \ce{Mn2O7} \):
\( \displaystyle \text{In } \ce{MnO4-}: x + 4(-2) = -1 \;\Rightarrow\; x = +7 \)
B. \( \ce{Sc^{3+}} \) (Scandium) is colourless — Correct. Sc (Z = 21) is [Ar]3d14s2; losing three electrons gives \( \ce{Sc^{3+}} \): 3d0, so no d–d transition is possible.
C. Brass is an alloy of Copper and Zinc — Correct. Transition metals form alloys readily because their atomic radii are similar, so atoms of one metal can take the place of the other in the lattice; brass is copper with zinc.
D. Lanthanide series included a total of 15 elements — Incorrect. The lanthanoids are the fourteen elements following lanthanum, cerium (Z = 58) to lutetium (Z = 71), in which the 4f subshell is filled.
E. \( \ce{V2O5} \) (Vanadium Pentaoxide) is used in the manufacturing of sulphuric acid (by contact process). — Correct. It catalyses the oxidation of \( \ce{SO2} \):
\( \displaystyle \ce{2SO2 + O2} \xrightarrow{\ce{V2O5}} \ce{2SO3} \)