Which of the following properties form Ce so Lu ?

Options

A. Hardness of elements
B. Melting points of elements
C. Boiling points element
D. Basic strength of Ln `(OH)_(3)`

Answer

D

Explanation

The atomic and ionic radii (`Ln^(3+)` ions) of lanthanides decrease with increasing atomic number (lanthanoidcontraction). It occurs because the poor shielding effect of 4f electrons is coupled with increased attraction between the nucleus and the added electrons. The hardness, meltin point and boiling point of elements increase from Ce to Lu because the attraction between the atoms increases as the size decreases. The basic strength of `Ln(OH)_(3)` decreases on account of increasing charge density of `Ln^(3+)` ion due to lanthanide contraction. Thus `Ce(OH)_(3)` is the most basic while `Lu(OH)_(3)` is the least basic.