In the 3d series of transition elements, the element more likely to exhibit +1 oxidation state is:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Cu
Copper has the configuration [Ar]3d104s1. Losing the single 4s electron gives \( \ce{Cu^{+}} \) with a completely filled 3d10 set, a stable arrangement. So copper is the 3d element that most readily shows the +1 oxidation state (\( \ce{Cu2O} \), CuCl, CuI, \( \ce{[Cu(CN)4]^{3-}} \)). In the table of oxidation states of the first row, +1 appears only for Cu.
Why the other options are incorrect
Option (1) Fe — Incorrect. [Ar]3d64s2; it shows +2 and +3; \( \ce{Fe^{+}} \) would have no stable configuration.
Option (2) Mn — Incorrect. [Ar]3d54s2; common states are +2 to +7, not +1.
Option (4) Ag — Incorrect. Ag does show +1, but silver is a 4d element (5th period), not a member of the 3d series.
NCERT (2026-27 edition):
Oxidation States – …
