The correct option is
B lanthanoid metals
The explanation for the Correct answer:
(B) Lanthanoid metals: Lanthanides are very dense metals having a higher melting point than the d-block elements.
- They combine with other metals to form alloys.
- These are elements of the f block, often referred to as inner transition metals.
- Inner transition elements and ions can have electrons in s, d, and f-, orbitals.
- Mischmetal – Well-known alloy is mischmetal which consists of Lanthanoid metal (~ 95%) and iron (~ 5%) and Traces of C, D, Ca, and Al.
The Explanation of all incorrect answers:
(A) Lanthanoid and actinoid metals: The first group of elements of the F series, known as the lanthanides, consists of substances whose atomic numbers range from 57 to 71.
- These substances do not emit radiation (except for promethium, which is radioactive).
- The second group of elements, known as actinides, consists of substances whose atomic numbers range from 89 to 103.
- These substances are generally radioactive in nature.
(C) Actinoid metals: The first element in the series, actinium, is where the name "actinide chain" originated.
- Any of the elements of the actinide series with atomic numbers 89 to 103 in the periodic table are represented by the symbol An.
(D) Actinoid and transition metals: The second group of elements of the F series, known as the actinides, consists of substances with atomic numbers ranging from 89 to 103, These substances are typically radioactive in nature.
- The f block components are called internal transition elements because the f orbital is closer to the nucleus than the d orbital.
Hence, Option(B) is correct.