Question

Which of the following is the correct order of arrangement of the first five lanthanides according to atomic number?

(a) La, Ce, Pr, Nd, Pm

(b) La, Pr, Ce, Pm, Nd

(c) La, Pr, Ce, Nd, Pm

(d) La, Ce, Pr, Pm, Nd

I had been asked this question during an interview for a job.

This key question is from D and F-Block Elements topic in section D and F-Block Elements of Chemistry – Class 12

Answer 1

Correct choice is (a) La, Ce, Pr, Nd, Pm

To elaborate: The first five elements of Lanthanides are:

Lanthanum (La) – 57

Cerium (Ce) – 58

Praseodymium (Pr) – 59

Neodymium (Nd) – 60

Promethium (Pm) – 61.