Question

Theoretical radii of atoms $<r_{max}>$ stay the same from left to right across the f-block in the sixth period, but real radii decreases across the f-block less rapidly than they do across the p-block.
If true enter 1, else enter 0.

Answer 1

Theoretical radii of atoms <rmax> stay the same from left to right across the f-block in the sixth period, but real radii decreases across the f-block less rapidly than they do across the p-block.
This is due to the higher screening effect of pre penultimate f electrons. Hence, the increase in the effective nuclear charge is more gradual for f block elements.