NTA Abhyas JEE Main2020Chemistryd and f Block ElementsPractice
Out of the following ions Ti 3 + , V 3 + , Cu + , Sc 3 + , Mn 2 + , Fe 3 + and Co 2 + the colourless ions will be
Options
- ACu + , Sc 3+
- BTi 3 + , V 3 +
- CCu + , Co 2 +
- DSc 3 + , Fe 3 +
Correct answer
A. Cu + , Sc 3+
Step-by-step solution
Only those ions will be coloured which have incomplete d - orbitals. Ions which has complete or vacant d - orbitals are colourless. Ti 3 + = [Ar] 3d 1 Purple V 3 + = [Ar] 3d 2 Green Cu + = [Ar] 3d 10 Colourless Sc 3 + = [Ar] Colourless Mn 2 + = [Ar] 3d 5 Pink Fe 3 + = [Ar] 3d 5 Brown Co 2 + = [Ar] 3d 7 Pink As Sc 3 + and Cu + have 3d 0 and 3d 10 configuration in their valence shell so their aqueous solutions are colourless. All others, i.e., Ti 3 + , V 3 + , Mn 2 + , Fe 3 + and Co 2 + are coloured in aqueous medium