Answer:
Hg, Tl, Pb, Bi.
Explanation:
The elements that are all in the same period are: Hg, Tl, Pb, Bi.
Kindly, find the attached image that show that all elements are in period 6.
Rb, Sr, La, Zr
:
All are in period 5 except La is in period 6.
Al, Ga, Si, P
:
All are in period 3 except Ga is in period 4.
N, O, Cl, Br:
N, and O are in period 2. While Cl is in period 3 and Br is in period 4.
