Question

Which block elements are known as inner transition elements?

(a) s-block

(b) p-block

(c) d-block

(d) f-block

This question was posed to me in an online quiz.

This question is from Electronic Configurations of Elements and the Periodic Table topic in portion Classification of Elements and Periodicity in Properties of Chemistry – Class 11

Answer 1

Correct answer is (d) f-block

For explanation: Inner transition elements are f-block i.e. 4f and 5f. They include elements from 57 to 71 and 89 to 103. The 4f elements are lanthanoids (57 – 71) and 5f are actinides (89 – 113). Most of the actinides are radioactive.