Eu
Ce
Tb
Dy
The correct option is (B): Ce
List-I Alkali Metal | List-II Emission Wavelength in nm |
---|---|
(A) Li | (I) 589.2 |
(B) Na | (II) 455.5 |
(C) Rb | (III) 670.8 |
(D) Cs | (IV) 780.0 |
Lanthanoids are at the top of these two-row, while actinoids are at the bottom row.
Lanthanoids are inclusive of 14 elements, with atomic numbers 58-71:
These elements are also called rare earth elements. They are found naturally on the earth, and they're all radioactively stable except promethium, which is radioactive. A trend is one of the interesting properties of the lanthanoid elements, called lanthanide contraction.