Answer
The period number is 6.
The group number is 8B.
Work Step by Step
The atomic number of Osmium is 76.
The electronic configuration is $[Xe] 4f^{14}5d^{6}6s^{2}$.
Here the valence shell is the sixth shell so it belongs to the sixth period.
It consists of partially filled d orbitals with 6 electrons and completely filled valence shell (6s) with 2 electrons, and hence the group number is 8B.
