Orange colour of `Cr_(2)O_(7)^(2-)` ion changes to yellow when treated with an alkali. Why ?

(a) (i) How is the variability in oxidation states of transition metals different from that of the p-block elements? (ii) Out of Cu^+ and Cu^(2+) , which ion is unstable in aqueous solution and why? (iii) Orange colour of Cr_2O_7^(2-) ion changes to yellow when treated with an alkali. Why? (b) Chemistry of actinoids is complicated as compared to lanthanoids. Give two reasons.

At pH=12,Cr_(2)O_(7)^(2-) changes to:

At pH = 11 , Cr_2O_7^(2-) ion changes to

When orange solution containing Cr_(2)O_(7)^(2-) ion is treated with an alkali, a yellow solution is formed and when H^(+) ions are added to yellow solution, an orange solution is obtained. Explain why does this happen?

K_(2)Cr_(2)O_(7)//H^(+) changes to green by

When orange solution containing Cr_(2)O_(7)^(2-) ion(A) is treated with an alkali, a yellow solution (B) is formed and when H^(+) ions are added to yellow solution, an orange solution is obtained.. What are A and B

(A) (C_(9)H_(12)O)underset(Hot KMnO_(4))overset([O])(rarr) PhCOOH i. (A) does not decolourise Br_(2) in C Cl_(4) , reacts with Na to give a colourless and odourless gas (B). ii. (A) does not give iodoform test. iii. (A) is a chiral compound and oxidation of (A) with CrO_(3)//Py gives a chiral compound (C ). iv. The colour of Cr_(2)O_(7)^(2-) change to blue-green when added to compound (A). The colour of Cr_(2)O_(7)^(2-) changes from orange to blue-green when added to compound (A). The blue-green colour is due to the formation of:

The colour of K_(2)Cr_(2)O_(7) solution changes with the change in pH of the medium. Why ?