Question

If the highest oxidation states shown by any Lanthanide and any Actinide are $+X$ and $+Y$, the sum of $X+Y$ is equal to?

Answer 1

Answer: 11

The lanthanide or lanthanoid series of chemical elements comprises the $15$ metallic chemical elements with atomic numbers $57$ to $71$ , from lanthanum through lutetium. The actinoid series encompasses the $15$ metallic chemical elements with atomic numbers from $89$ to $103$ , from actinium through lawrencium.
Lanthanide $[Ce=+4]$
Actinide $[Np=+7]$
Sum of $X+Y=4+7=11$