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Question : 24
Total: 26
(a) Account for the following:
(i) Transition metals show variable oxidation states.
(ii)Zn , Cd Hg
(iii)E ∘ Mn 3 + ∕ Mn 2 + ( + 1.57 V ) Cr 3 + ∕ Cr 2 +
(b) Write one similarity and one difference between the chemistry of lanthanoid and actinoid elements.
OR
(a) Following are the transition metal ions of3 d
Ti 4 + , V 2 + , Mn 3 + , Cr 3 +
(Atomic numbers:Ti = 22 , V = 23 , Mn = 25 Cr = 24
Answer the following :
(i) Which ion is most stable in an aqueous solution and why?
(ii) Which ion is a strong oxidising agent and why?
(iii) Which ion is colourless and why?
(b) Complete the following equations:
(i)2 MnO 4 − + 16 H + + 5 S 2 − →
(ii)KMnO 4
(i) Transition metals show variable oxidation states.
(ii)
(iii)
(b) Write one similarity and one difference between the chemistry of lanthanoid and actinoid elements.
OR
(a) Following are the transition metal ions of
(Atomic numbers:
Answer the following :
(i) Which ion is most stable in an aqueous solution and why?
(ii) Which ion is a strong oxidising agent and why?
(iii) Which ion is colourless and why?
(b) Complete the following equations:
(i)
(ii)
Solution:
(a) (i) Transition metals show variable oxidation states because of the small difference in energy of the ns and ( n − 1 ) d n s ( n − 1 ) d
(ii)Zn , Cd Hg
(iii) BecauseMn 2 + d 5 Cr 3 + t 2 g 3 .
(b) Similarity-both are stable in +3 oxidation state/ both show contraction/ irregular electronic configuration (or any other suitable similarity)
Difference-actinoids are radioactive and lanthanoids are not / actinoids show wide range of oxidation states but lanthanoids don't (or any other correct difference).
OR
(a) (i)Cr 3 +
(ii)Mn 3 + E ∘ ( M 3 + ∕ M 2 + )
(iii)Ti 4 +
Electronic configuration :1 S 2 2 S 2 2 p 6 3 S 2 3 p 6 4 S 2 3 d ∘
It has completely emptyd d − d
(b) (i)2 MnO 4 − + 16 H + + 5 S 2 − → 5 S + 2 Mn 2 + + 8 H 2 O
(ii)2 KMnO 4 → K 2 MnO 4 + MnO 2 + O 2
(ii)
(iii) Because
(b) Similarity-both are stable in +3 oxidation state/ both show contraction/ irregular electronic configuration (or any other suitable similarity)
Difference-actinoids are radioactive and lanthanoids are not / actinoids show wide range of oxidation states but lanthanoids don't (or any other correct difference).
OR
(a) (i)
(ii)
(iii)
Electronic configuration :
It has completely empty
(b) (i)
(ii)
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