Which among the following actinoids does not have stable electronic...

Protactinium $\left(Pa\right)$ is the element that does not have stable electronic configuration.

Protactinium $\left(Pa\right) = \left[Rn\right]5f^{2}6d^{1}7s^{2}$ (Atomic number $= 91$)

Nobelium \left(No\right) = \left(Rn\right)5f^{14}6d^{0}7s^{2}$~(Atomic number$= 102$)</p><p>Lawrencium \left(Lr\right) = \left[Rn\right]5f^{14}6d^{1}7s^{2}$ (Atomic number $= 103$)

Americium \left(Am\right) = \left[Rn\right]5f^{7}6d^{0}7s^{2}$(Atomic number$= 95)