MCQ
Lanthanoids are
- ✓$14$ elements in the sixth period (atomic no.$ = 58$ to $71$) that are filling $4f$ sublevel
- B$14$ elements in the seventh period (atomic no. $= 58$ to $ 71$) that are filling $4f$ sublevel
- C$14 $ elements in the sixth period (atomic no. $= 90$ to $103$) that are filling 4f sublevel
- D$14$ elements in the seventh period (atomic no. $ = 90$ to $103$) that are filling $ 4f$ sublevel
