The electronic configuration (outermost) of $Mn^{2+}$ ion (atomic number of $Mn = 25$) in its ground state is

Select the $CORRECT$ set of group number and period of element $Uub$ (Ununbium,now known as Copernicium,$Cn$).

Assertion $(A)$: While going from left to right in the periodic table,the atomic size decreases more rapidly for the $3d$-series compared to the $4f$-series of elements.
Reason $(R)$: $3d$-electrons experience lesser shielding than $4f$-electrons.

Which of the following elements is $NOT$ regarded as a transition element?

Platinum, Palladium and Iridium are called noble metals because

Which among the following elements does not have any electron in the $f-$subshell in either its expected or observed electronic configuration?