1.

Which one of the following statements related to lanthanons is incorrect ?

Answer»

All the lanthanons are much more reactive than aluminium
`Ce(+4)` solutions are widelyused as oxidizing agent in volumetric analysis
Europium SHOWS `+2` oxidation state
The basicity decreases as the ionic radius decreases from Pr to Lu.

Solution :(a) Lnathnons are less reactivethan aluminium due tohigh IP ( Lanthanoid contraction)
(B) `Ce^(+4)` is good oxidizing agent and easily converted into `Ce^(+3)`
(c ) Eu ( 63) `= 4f^(7) 5d^(0)6s^(2) ,Eu^(+2)= 4f^(7)`
(d) In lanthanoids series 'Ce' to 'Lu' ionic radius REGULARLY decreases and covalent character increases and hence BASIC character of hydroxides decreses.


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