Question

Out of TiF₆²⁻ , CoF₆³⁻ , Cu₂Cl₂ and NiCl₄²⁻ (Z of Ti = 22,
Co = 27, Cu = 29, Ni = 28), the colourless species are:
(a) Cu₂Cl₂ and NiCl₄²⁻ (b) TiF₆²⁻ ,and Cu₂Cl₂
(c) CoF₆³⁻ ,and NiCl₄²⁻ (d) TiF₆²⁻ ,and CoF₆³⁻

Answer 1

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Cu₂Cl₂ and NiCl₄²⁻

Answer 2

The colourless species are (b) TiF₆²⁻ ,and Cu₂Cl₂

The colour of the element depends on the unpaired electron. The colour is produced because of energy difference between the level.

TiF₆²⁻:

The tin present in TiF₆²⁻ is Ti⁴⁺.

The electronic configuration of Ti⁴⁺ is:

$\mathrm{Ti}^{4+}=[\mathrm{Ar}] 3 \mathrm{d}^{0} 4 \mathrm{s}^{0}$

It has no unpaired electron, so, it is colourless in nature.

Cu₂Cl₂:

The copper present in Cu₂Cl₂ in Cu⁺.

The electronic configuration of Cu⁺ is:

$\mathrm{Cu}^{+}=[\mathrm{Ar}] 3 \mathrm{d}^{10} 4 \mathrm{s}^{0}$

It has no unpaired electron, so, it is colourless in nature.

Since, there are no electron in the valence shell. The electrons cannot transfers from one energy level to another.