# Knowing that the chemistry of lanthanoids $\dpi{100} \left ( Ln \right )$ is dominated by its $\dpi{100} +3$ oxidation state, which of the following statements is incorrect ? Option 1) Because of the large size of the $Ln (III)$ ions the bonding in its compounds is predominantly ionic in character . Option 2) The ionic sizes of $Ln (III)$ decrease in general with increasing atomic number. Option 3) $Ln (III)$ compounds are generally colourless. Option 4) $Ln (III)$ hydroxide  are  mainly  basic in  character

As we learnt in

As atomic radii, ionic radii also decrease with increase in atomic number.In +3 oxidation state.

-

and

Lanthanoid contraction -

The filling of if orbits before 5d orbits result regular decrease in atomic radii called Lanthanoid contraction or can say the size of radii not much increase.

- wherein

$e.g.\:\:\:\:3d\rightarrow 4d\rightarrow 5d$

Due to large size bonding of $Ln\left ( III \right )$ is ionic. The ionic size of $Ln\left ( III \right )$ decreases on increasing atomic number  i.e. due to lanthanoid contraction Hydroxide of $Ln\left ( III \right )$ are mainly basic in nature. $Ln\left ( III \right )$ compounds are generally colourless.

Option 1)

Because of the large size of the $Ln (III)$ ions the bonding in its compounds is predominantly ionic in character .

This option is incorrect.

Option 2)

The ionic sizes of $Ln (III)$ decrease in general with increasing atomic number.

This option is incorrect.

Option 3)

$Ln (III)$ compounds are generally colourless.

This option is correct.

Option 4)

$Ln (III)$ hydroxide  are  mainly  basic in  character

This option is incorrect.

### Preparation Products

##### JEE Main Rank Booster 2021

This course will help student to be better prepared and study in the right direction for JEE Main..

₹ 13999/- ₹ 9999/-
##### Knockout JEE Main April 2021 (Subscription)

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 6999/- ₹ 5/-
##### Knockout JEE Main April 2021

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 22999/- ₹ 14999/-
##### Knockout JEE Main April 2022

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 34999/- ₹ 24999/-