(i)with reference to structural variability and chemical reactivity write the differences between lanthanoids and actinoids
(ii) Mame a member of the lanthanoid series which is well known to exhibit +4 oxidation state
(iii) Complete the following equation :`MnO_(4)^(-)+8H^(+)+5e^(-)rarr`
(iv) out of `Mn^(3+)` and `Cr^(3+)` which is ore paramagnetic and why? Atomic nos : Mn =25 Cr =24

(i) Name the element of 3d transition series which shows maximum number of oxidation states. Why does it show so ? (ii)Which transition metal of 3d series ha positive E^(@)(M^(2+)//M) value and why ? (iii) Out of Cr^(3+) and Mn^(3+) , which is a stronger oxidizing agent and why ? (iv) Name a member of the lanthanoid series which is well known to exhibit + 2 oxidation state. (v) Complete the following equation : MnO_(4)^(-) + 8H^(+) + 5e^(-) to .

Name the following: (a) A transition metal which does not exhibit variation in oxidation state in its compounds. (b) A compound where the transition metal is the +7 oxidation state. (c) A member of the lanthanoid series which is well known to exhibit +4 oxidation state. (d) Ore used in the preparation of Potassium dichromate.

Complete the following chemical equations : (i) 8MnO_(4)^(-)+3S_(2)O_(3)^(2-)+H_(2)O to (ii) Cr_(2)O_(7)^(2-)+3Sn^(2+)+14H^(+) to

(a) Give three points of difference between lanthanoids and actinoids. (b) Give reason and select on one atom/ion which will exhibit asked property: (i) Sc^(3+) or Cr^(3+) (exhibit diamagnetic behaviour) (ii) Cr or Cu (high melting and boiling point)

(i) Which transition element in 3d series has positive E_(M^(2+//)M)^(@) value and why ? (ii) Name a member of lanthanoid series which is well known to exhibit to exhibit +4 oxidation state and why? (b) Account for the following : (i) The highest oxidation state is exhibited in oxoanions of transition metals. (ii) HCl is not used to acidify KMnO_(4) solution. (iii) Transition metals have high enthalpy of atomisation.