Match List I with List II.
|
LIST I |
LIST II |
|
A. Ni |
I. 3d Series |
|
B. Cu |
II. Lanthanoid contraction |
|
C. Gd |
III. \(d^{10}\) |
|
D. Cs |
IV. Alkali metal |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → A-I, B-III, C-II, D-IV
The place of an element in the periodic table follows from the subshell its last electron enters: d-block elements fill (n−1)d orbitals (3d for the first series, Sc to Zn), lanthanoids fill 4f orbitals, and alkali metals have a single ns electron.
A. Ni — This matches I. 3d Series. Ni (Z = 28) is [Ar]3d84s2, a member of the first (3d) transition series.
B. Cu — This matches III. d10. Cu (Z = 29) is [Ar]3d104s1: one 4s electron moves into 3d because a completely filled d10 subshell is extra stable.
C. Gd — This matches II. Lanthanoid contraction. Gd (Z = 64), [Xe]4f75d16s2, is a lanthanoid; across the lanthanoids the atomic and ionic radii decrease steadily because the 4f electrons shield the growing nuclear charge poorly.
D. Cs — This matches IV. Alkali metal. Cs (Z = 55) is [Xe]6s1, a group 1 element.
Shortcut: C-II (Gd with the lanthanoid contraction) appears only in Option (2).