The trivalent ion having size in lanthanide series is

Which trivalent ion has maximum size in the lanthanoid series i.e., Lanthanum ion (La^(3+)) to Lutetium ion (Lu^(3+)) ? (At. no. of lanthanum = 57 and lutetium = 71)

Which trivalent cation is largest in lanthanoid series ?

The size of the trivalent cations in the lanthanoid series decreases steadily as the atomic number increases. What is this known as ?

The size of the trivalent cations in the lanthanoid series decrease steadily as the atomic number increases. What is this known as ?