JEE Main · 2020 · 04 Sep 2020 · Shift 1 · d and f Block Elements

Element $101$ is mendelevium, which lies in the actinoid series where the $5f$ orbitals are being filled. Element $104$ is rutherfordium, the first transactinide; with an outer configuration like $6d^{2}7s^2$ it sits below hafnium in Group $4$. So the two elements belong to the actinoids and to Group $4$, respectively.