Question:
The elements with atomic numbers 101 and 104 belong to, respectively:
Correct Option: , 3
Solution:
${ }_{89} \mathrm{AC} \longrightarrow{ }_{103} \mathrm{Lr}$
Belongs to actinoids series and they all belongs to $3^{\mathrm{rd}}$ group. So atomic no. 101 element is actinoids and atomic number 104 element belongs to $4^{\text {th }}$ group.