(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)

Decide giving reasons which one of the following exhibits the property indicated :L (i) Sc^(3+) and Cr^(3+) exhibit paramanetism (ii) V or Mn exhibits more number of oxidation sates (at. No Sc= 21 , V =23 , Cr = 24 , Mn=25)

(i)with reference to structural variability and chemical reactivity write the differences between lanthanoids and actinoids (ii) Name a member of the lanthanoid series which is well known to exhibit +4 oxidation state

Describe giving reason which one of the following pairs has the property indicated? (a). Fe or Cu has higher melting point. (b). Co^(2+) or Ni^(2+) has lower magnetic moment.

Give reasons for the following: (i) Binary compounds of oxygen and fluorine are called fluorides. (ii) Fluorine forms only one oxoacid HOF. (iii) Noble gases have very low melting and boiling points.

Explain giving reason: (i) Treansition metals and their compounds generally exhibit a paramagnetic behave . (ii) The chemistry of actinoids is not so smooth as that of lanthanoids.

(a) Complete the following chemical equations for reactions : (i) MnO_(4(aq))^(-) + S_(2)O_(3(aq))^(2-) + H_(2)O_((l)) to (ii) Cr_(2)O_(7 (aq))^(2-) + H_(2)S_((g)) + H_((aq))^(+) to (b) Give an explanation for each of the following observations : (i) The gradual decrease in size (actinoid contraction) from element to element is greater among the actinoids than that among the lanthanoids (lanthanoid contraction.) (ii) The greatest number of oxidation states are exhibited by the members in the middle of a transition series. (iii) With the same d-orbitals configuration (d^(4)) Cr^(2+) ion is a reducing agent but Mn^(3+) ion is an oxidising agent .

Give an explanation for each of the following observations: (i) The gradual decrease in size (actinoid con-traction) from element to element is greater among the actinoids than that among the lanthanoids (lanthanoid contraction). (ii) The greater number of oxidation states are exhibited by the members in the middle of a transition series. (iii) With the same d-orbital (d^4) , Cr^(2+) ion is a reducing agent but Mn^(3+) ion is an oxidising agent.

(a) Though nitrogen exhibits +5 oxidation state, it does not form pentahalide. Give reason. (b) PH_3 has lower boiling point than NH_3 . Why ?

(a) Though nitrogen exhibits +5 oxidation state, it does not form pentahalide. Give reason. (b) PH_3 has lower boiling point than NH_3 . Why ?

Ionic bond is defined as the electrostatic force of attraction holding the oppositely charged ions. Ionic compounds are mostly crystalline solid having high melting and boiling points, electrical conductivity in moleten state, solubility in water etc. Covalent bond is defined as the force which binds atoms of same or different elements by mutual sharing of electrons in a covalent bond. Covalent compounds are solids, liquids or gases. They have low melting and boiling points compounds. They are more soluble in non-polar solvents. Which of the following is arranged order of increasing boiling point ?