The Crystal Field Stabilisation Energy $(CFSE)$ for $[CoCl_{6}]^{4-}$ is $18000 \; cm^{-1}$. The $CFSE$ for $[CoCl_{4}]^{2-}$ will be $...... \ cm^{-1}$.

Which of the following is the strongest field ligand?

The correct order of energy of absorption for the following metal complexes is
$A: [Ni(en)_3]^{2+}, B: [Ni(NH_3)_6]^{2+}, C: [Ni(H_2O)_6]^{2+}$

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: $[CoCl(NH_3)_5]^{2+}$ absorbs at a lower wavelength of light with respect to $[Co(NH_3)_5(H_2O)]^{3+}$.
Reason $R$: It is because the wavelength of the light absorbed depends on the oxidation state of the metal ion.
In the light of the above statements,choose the correct answer from the options given below:

The tetrahedral crystal field splitting energy is equal to ................. of the octahedral crystal field splitting energy.

In which complex is the wavelength of absorbed light the lowest?