What is lanthanoid contraction?

(a) Why do transition elements show variable oxidation states? (i) Name the element showing maximum number of oxidation states among the first series of transition metals from Sc (Z = 21) to Zn (Z = 30). (ii) Name the element which shows only + 3 oxidation state. (b) What is lanthanoid contraction? Name an important alloy which contains some of the lanthanoid metals.

(a) How would you account for the following : (i) Cobalt (II) is stable in aqueous solution but in the presence of strong ligands, it is easily oxidised. (ii) The transition metals form interstitial compounds. (iii) Silver halides find use in photography. (b) What is lanthanoid contraction ? Mention its main consequences.

(a) What is Lanthanoids contraction ? (b) What are Interstial compounds ? Give one example (c) Calculate the spin only magnetic moment of M^(2+)(aq) ion [Z=29].

What is meant by 'lanthanoid contraction'?

What is meant by lanthanoids contraction ? What effect does it have on the chemistry of element which follow lanthanoids ?

(a) What is the cause of lanthanoid contraction? Discuss. (b) What is Misch metal?

(a) Why do transition elements show catalytic properties? (b) Calculate equivalent weight of KMnO_4 in neutral medium. ( c) What is the cause of lanthanoid contraction?