Which of the following is incorrect ?

Options

A. Ionisation enthalpies of the early actionoids are higher than for the early lanthanoids
B. Unlike lanthanoids, actinoids form oxocations
C. Oxides and hydroxides of actinoids are more basis than those of lanthanoids
D. Ion exchange behaviour is exhibited by both actinides and lamnthanides.

Answer

A

Explanation

Because 5d electrons penetrarte less into the inner core of electrons. Therefore, the 5f electrons of actinoids are more effectively shielded form the nuclear charge than the 4f electrons of the are less firmly held, they are easily available for bonding in the actionids. Lanthanoids do not form oxocations while actinoids form oxocations such as `UO_(2)^(2+)`, `UO^(+)`, `UO_(2)^(+)`, etc. These ions decreases in the order.
`M^(4+) gt MO_(2)^(2+) gt M^(3+) gt MO_(2)^(+)`
This is because higher the charge density (i.e. higher the charge and smaller the ionic size), more is the complex forming ability. The higher tendency of complex formation of `MO_(2)^(2+)` ion as compared to `M^(3+)` is due to higher conc. of charge metal atom M in `MO_(2)^(2+)` .