How many geometrical isomers are possible for the square planar complex $[Pt(NO_2)(Py)(NH_3)(NO_2)]$?

The number of isomers possible for the square planar complex $K_2[PdClBr_2(SCN)]$ is

In which case is a racemic mixture obtained upon mixing its mirror images ($d$ and $l$ forms) in a $1:1$ molar ratio?

Which of the following ions has the lowest magnetic moment?

Select the correct code of $TRUE$ and $FALSE$ for the given statements:
$(a)$ Peroxide ion as well as dioxygen molecule both are paramagnetic species.
$(b)$ In the set of isomers,$[Cr(H_2O)_6]Cl_3$ and $[CrCl(H_2O)_5]Cl_2 \cdot H_2O$,both compounds can easily lose water molecules on treatment with conc. $H_2SO_4$.
$(c)$ During the transformation $NO \to NO^+$,bond length decreases and magnetic behavior changes from paramagnetic to diamagnetic.
$(d)$ An ether is more volatile than an alcohol,both having the same molecular formula.

What is the spin-only magnetic moment of an element having one unpaired electron (in $BM$)?