The gradual decrease in atomic radius for lanthanoids element in not obeyed by

The atomic radius of which element is least

Give an explanation for the following observation : The gradual decrease in size (actinoid contraction) from element to element is greater among the actinoids than that among the lanthanoids (lanthanoid contraction).

The correct decreasing order atomic radius is:

The gradual decrease in size (actionoid contraction) is from element to element is greater among the actinoids than that among the lanthanoids (lanthanoid contraction).

The atomic radius decrease in a period due to

Why the decrease in atomic radius amongst a series of transition elements is less when compared with representative elements ?

The atomic radius decreases in a period due to