Which of the following mixtures can form an alloy?

Among the following transition elements,which one has the lowest first ionization energy?

The $3d$ elements show variable oxidation states because the energies of the following sets of orbitals are almost similar:

Which elements were named by the following?
$(i)$ Lawrence Berkeley Laboratory
$(ii)$ Seaborg's group

Which of the following pairs of ions have the same paramagnetic moment?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A):$ $Cu^{2+}$ in water is more stable than $Cu^{+}$.
Reason $(R):$ Enthalpy of hydration for $Cu^{2+}$ is much less than that of $Cu^{+}$.
In the light of the above statements,choose the correct answer from the options given below: