NCERT Class XII Chemistry
Chapter - The d- and f-Block Elements
Questions with Solutions
© examsnet.com
Question : 25
Total: 49
Give examples and suggest reasons for the following features of the transition metal chemistry :
(i) The lowest oxide of transition metal is basic, the highest is amphoteric/ acidic.
(ii) A transition metal exhibits highest oxidation state in oxides and fluorides.
(iii) The highest oxidation state is exhibited in oxoanions of a metal.
(i) The lowest oxide of transition metal is basic, the highest is amphoteric/ acidic.
(ii) A transition metal exhibits highest oxidation state in oxides and fluorides.
(iii) The highest oxidation state is exhibited in oxoanions of a metal.
Solution:
(i) Lowest oxidation compounds of transition metals are basic dueto their ability to get oxidised to higher oxidation states. Whereas thehigher oxidation state of metal and compounds gets reduced to lowerones and hence acts as acidic in nature.
e.g. MnO is basic whereasM n 2 O 7
(ii) Due to high electronegativities of oxygen and fluorine, the oxides andfluorides of transition metals exhibit highest oxidation state.
e . g . O s F 6 , V 2 O 5
(iii) In oxoanions of metals, the metals from bonds with oxygen andhence are present in their highest oxidation states. For example : Cr formsC r O 4 2 – C r 2 O 7 2 –
Permanganate ion,M n O 4 –
e.g. MnO is basic whereas
(ii) Due to high electronegativities of oxygen and fluorine, the oxides andfluorides of transition metals exhibit highest oxidation state.
(iii) In oxoanions of metals, the metals from bonds with oxygen andhence are present in their highest oxidation states. For example : Cr forms
Permanganate ion,
© examsnet.com
Go to Question: