Which of the following is the correct order in the spectrochemical series of ligands?

Compound $PdCl_4 \cdot 6H_2O$ is a hydrated complex; $1 \ m$ aqueous solution of it has a freezing point of $269.28 \ K$. Assuming $100\%$ ionization of the complex,calculate the molecular formula of the complex ($K_f$ for water $= 1.86 \ K \ kg \ mol^{-1}$,freezing point of pure water $= 273 \ K$).

The reaction of $CuSO_4$ with excess $KCN$ solution leads to the formation of:

In the isoelectronic series of metal carbonyls,the $CO$ bond strength is expected to increase in the order:

Assertion : $[Al(H_2O)_6]^{3+}$ is a stronger acid than $[Mg(H_2O)_6]^{2+}$.
Reason : Size of $[Al(H_2O)_6]^{3+}$ is smaller than $[Mg(H_2O)_6]^{2+}$ and possesses more effective nuclear charge.

Calculate the overall complex dissociation equilibrium constant for the $Cu(NH_3)_4^{2+}$ ion,given that $\beta_4$ for this complex is $2.1 \times 10^{13}$.