The `+3` oxidation states of langthanum `( Z= 57)`, gadolinium `(Z= 64)` and lutetium `(Z= 71)` are especially stable. Why ?

(a). Of the lanthanides, cerium (Z=58) forms a tetrapositive ion, Ce^(4+) in aqueous solution. Why? (b), The +3 oxidation states of lanthanum (Z=57) , gadolinium (Z=64) and lutetium (Z=71) are especially stable. Why? (c). Why Zr and or Nb anbd Ta exhibit similar properties ? (d). Which oiut of the two La(OH)_3 and Lu(OH)_3 , is more basic and why?

The common oxidation states of element with z = 24 is

Give the electronic configuration of Europium (Z=63) and Gadolinium (Z=64)

Identify the oxidation states of titinium (Z=22) and copper (Z=29) in their colourless compounds.

The maximum spin only magnetic moment in ground state of Gadolinium (Z = 64).

The number of unpaired electrons in gadolinium (Z=64) is :

(a) Out of Cu^+ and V^(2+) which will be coloured and why? (Atomic number of V is 23 and Cu is 29). (b) Why is + 3 oxidation state of Fe (Z = 26) more stable than its + 2 oxidation state? ( c) Is Au (Z = 79) a transition metal or not? Explain.

The most stable state of Ce (Z = 58) is