Which of the following elements does not belong to the first transition series?

Although $Cr^{3+}$ and $Co^{2+}$ ions have the same number of unpaired electrons,the magnetic moment of $Cr^{3+}$ is $3.87 \ BM$ and that of $Co^{2+}$ is $4.87 \ BM$. Why?

The elements with the highest and the lowest enthalpy of atomisation respectively, for first row transition elements are:

What is the number of electrons present in the $d$-subshell if the atomic number is $27$ and the oxidation state is $+2$?

The maximum and minimum melting points of the first and second transition series elements,respectively,are obtained with $-$

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: The first ionization enthalpy of $3d$ series elements is more than that of group $2$ metals.
Reason $(R)$: In $3d$ series of elements,successive filling of $d$-orbitals takes place.
In the light of the above statements,choose the correct answer from the options given below: