The complex ion $[Cu(NH_3)_4]^{2+}$ is:

Which of the following complexes does not exhibit $d^2sp^3$ hybridization?

The geometry of the cuprammonium ion $[Cu(NH_3)_4]^{2+}$ is:

Number of identical $Cr-O$ bonds in dichromate ion $Cr_2O_7^{2-}$ is

According to Werner’s theory,the geometry of the complex is determined by:

Given below are two statements :
Statement $I$: $[Ni(CN)_4]^{2-}$ is square planar and diamagnetic complex with $dsp^2$ hybridization for $Ni$ but $[Ni(CO)_4]$ is tetrahedral,diamagnetic and with $sp^3$ hybridization for $Ni$.
Statement $II$: $[NiCl_4]^{2-}$ and $[Ni(CO)_4]$ both have same $d$-electron configuration,have same geometry and are paramagnetic.
In light of the above statements,choose the correct answer from the options given below: