$CuSO_4 \cdot 5 H_2O$ is blue in colour while $CuSO_4$ is colourless. Why?

Crystal field stabilization energy for high spin $d^4$ octahedral complex is

Simplified absorption spectra of three complexes $(i), (ii)$ and $(iii)$ of $M^{n+}$ ion are provided below; their $\lambda_{max}$ values are marked as $A, B$ and $C$ respectively. The correct match between the complexes and their $\lambda_{max}$ values is
$(i)$ $[M(NCS)_6]^{(-6+n)}$
$(ii)$ $[MF_6]^{(-6+n)}$
$(iii)$ $[M(NH_3)_6]^{n+}$

Which of the following correctly represents the order of ligands in the spectrochemical series?

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:

What is the correct order of increasing field strength for the ligands $NH_3$,$en$,$CN^-$,and $CO$?