How many elements are counted as rare earth elements?
- A30: the lanthanides and actinides
- B14: the lanthanides except promethium
- C17: the 15 lanthanides plus scandium and yttrium
- D15: the lanthanides only
Show answer and explanation
Correct answer: (c) 17: the 15 lanthanides plus scandium and yttrium
Explanation
There are 17 rare earths: 15 lanthanides, scandium and yttrium. They are "rare" because they are hard to find in concentrated deposits and hard to separate.