The number of unpaired electrons in $Cr^{+}$ will be

The second and third rows of transition elements resemble each other much more than they resemble the first row. Explain why?

State the reason for the stability of the $Gd^{3+}$ ion.

Explain the variations in atomic radii of transition elements along the period. The following table provides data for the first transition series:

Element	Sc	Ti	$V$	Cr	Mn	Fe	Co	Ni	Cu	Zn
Metallic Radius $M$ (pm)	$164$	$147$	$135$	$129$	$137$	$126$	$125$	$125$	$128$	$137$

Which cation from the following develops the least magnetic moment?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$. Assertion $(A)$: In aqueous solutions $Cr^{2+}$ is reducing while $Mn^{3+}$ is oxidising in nature.
Reason $(R)$: Extra stability to half-filled electronic configuration is observed than incompletely filled electronic configuration.
In the light of the above statement,choose the most appropriate answer from the options given below: