Which of the following complexes will exhibit the highest number of isomers?

The complex ion $[Pt(NO_2)(Py)(NH_3)(NH_2OH)]^+$ will give $..........$ geometrical isomers.

Which of the following compounds has a magnetic moment of $\sqrt{15} \ B.M.$?

Which of the following complexes does not exhibit optical isomerism?

Given below are two statements:
Statement-$I$ : The number of paramagnetic species among $[CoF_6]^{3-}$, $[TiF_6]^{3-}$, $V_2O_5$ and $[Fe(CN)_6]^{3-}$ is $3$.
Statement-$II$ : $K_4[Fe(CN)_6] < K_3[Fe(CN)_6] < [Fe(H_2O)_6]SO_4 \cdot H_2O < [Fe(H_2O)_6]Cl_3$ is the correct order in terms of number of unpaired electron$(s)$ in the complexes.
In the light of the above statements, choose the correct answer from the options given below.

For a transition metal with a $d^7$ configuration,the magnetic susceptibility (magnetic moment) is ........ $B.M.$