# Please explain me iiiB group of the periodic table.?? Thank you.

It is usually considered to contain the entire $f$-block, but it doesn't really matter. I would have said $\text{La}$ and $\text{Ac}$ are the only lanthanide or actinide in group $\text{IIIB}$, since they don't have outer-core $f$ electrons.
But, it seems that group $\text{IIIB}$ contains $\text{Sc}$, $\text{Y}$, and $\text{La" - "Lu}$, and $\text{Ac" - "Lr}$.
either of which would have shown the first or last $f$ block element as in group $\text{IIIB}$. Honestly, it doesn't really matter.