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Give reasons for the following: i. Tra...

Give reasons for the following:
i. Transition elements act as catalysts
ii. It is difficult to obtain oxidation state greater than two for Copper.
iii. CrO is basic but `Cr_(2)O_(3)` is amphoteric.

Text Solution

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(i) Due to large surface area and ability to show variable oxidation states
(ii)Due to high value of third ionisation enthalpy
(iii) Oxidation state of Cr in `Cr_(2)O_(3)` is `+3` and of CrO is +2. When oxidation number of a metal increases, ionic character decreases so CrO is basic while `Cr_(2)O_(3)` is amphoteric.
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