Question:

The elements with atomic numbers 101 and 104 belong to, respectively:

1. Group 11 and Group 4

2. Actinoids and Group 6

3. Actinoids and Group 4

4. Group 6 and Actinoids

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.