Q. Actinides
A) Have variable valency
B) Include element 12
C) Are all synthetic elements
D) Have only short lived isotopes
Explanation
(a)
Actinides have variable valency due to very small difference in energies of $5f,\ 6d$ and $7s$ orbitals
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.