MHT CET202526 Apr 2025Morning ShiftChemistryCoordination CompoundsActual
Which from following compounds contains complex anions?
Options
- ASodium hexanitrocobaltate (III)
- BTriamminetrinitrocobalt (III)
- CPentaammineaquacobalt (III) iodide
- DTriamminetrinitrocobalt (III)
Correct answer
A. Sodium hexanitrocobaltate (III)
Step-by-step solution
A complex anion is identified by the -ate suffix applied to the name of the central metal atom. In sodium hexanitrocobaltate(III), the term cobaltate clearly denotes a complex anion, with sodium as the counterion. In contrast, triamminetrinitrocobalt(III) and pentaammineaquacobalt(III) iodide involve neutral or cationic cobalt complexes, lacking the -ate suffix. Only sodium hexanitrocobaltate(III) contains a complex anion.