Which of the following ions will exhibit colour in aqueous solutions?Sc3+ (z = 21)La3+ (z = 57)Ti3+ (z = 22)Lu3+ (z = 71)

The color of ions in aqueous solutions is generally due to d-d transitions of light. This means that ions with partially filled d-orbitals often exhibit color in aqueous solutions.

1. Sc3+ (z = 21): Scandium (Sc) has an atomic number of 21. In its +3 oxidation state, it loses all 3 of its 4s and 3d electrons, leaving it with a completely filled 3p6 configuration. Therefore, Sc3+ does not have any d-d transitions and will not exhibit color in aqueous solutions.

2. La3+ (z = 57): Lanthanum (La) has an atomic number of 57. In its +3 oxidation state, it loses its 2 6s electrons and one 5d electron, leaving it with a completely filled 4f14 5d0 configuration. Therefore, La3+ does not have any d-d transitions and will not exhibit color in aqueous solutions.

3. Ti3+ (z = 22): Titanium (Ti) has an atomic number of 22. In its +3 oxidation state, it loses its 2 4s electrons and one 3d electron, leaving it with a partially filled 3d1 configuration. Therefore, Ti3+ does have d-d transitions and will exhibit color in aqueous solutions.

4. Lu3+ (z = 71): Lutetium (Lu) has an atomic number of 71. In its +3 oxidation state, it loses its 2 6s electrons and one 5d electron, leaving it with a completely filled 4f14 5d0 configuration. Therefore, Lu3+ does not have any d-d transitions and will not exhibit color in aqueous solutions.

So, out of the given ions, only Ti3+ will exhibit color in aqueous solutions.