Explanation
Which of the following pairs has almost same colour?
Correct Answer: Option C
The oxidation state of chromium in K2Cr2O7 is +6, whereas the oxidation state of nitrogen in HNO3 is +5.
Since the maximum oxidation state of nitrogen is +5, so it won’t get oxidize further. Rather it will react to form dichromate ion and a water molecule ( Cr2O2−7 and H2O ).
The equation involved is:
2K2CrO4+2HNO3→K2Cr2O7+2KNO3+H2O
Therefore, when potassium chromate solution is treated with an excess of dilute nitric acid, Cr2O2−7 and H2O are formed.
The actinoids exhibit more number of oxidation states in general than lanthanoids because:
Correct Answer: Option D
Explanation:
The common oxidation number of lanthanoid is +3 but +2 and +4 ions are also found in the solution.
Actinoids show +3 as oxidation state but some Actinoids are stable till +7 oxidation states.
Actinoids have more oxidation states than the Lanthanoids as 5f orbitals are at a greater distance from the nucleus than 4f orbitals.
Therefore lanthanoids are larger in size than in comparison to actinoids.
The catalytic activity of transition metals is attributed to the following reason. Because of their variable oxidation states transition metals sometimes form unstable intermediate compounds and provide a new path with a lower activation energy for the reaction.
Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.
Both Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1.
Statement 1 is correct but Statement 2 is not correct.
Statement 1 is not correct but Statement 2 is correct.
Both the Statement 1 and Statement 2 are not correct.
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