Question

How many of the following are lanthanides?
Uranium, praseodymium, erbium, gadolinium, curium, hafnium, osmium, iridium

Answer 1

Answer: 3

Praseodymium $\text{(Pr),}$ erbium $\left(\text{Er}\right)$ and gadolinium $\left(\text{Gd}\right)$ are lanthanoids.