What happens when: i) K2Cr 2O7 reacts with an acidified solution of FeSO4? (ii) KMnO4 reacts with an acidified solution of KI?

(1)6 FeSO4 + K2Cr2O7 + 7 H2SO4 = 3 Fe2(SO4)3 + K2SO4 + Cr2(SO4)3 + 7 H2O

(2)Permanganate reaction in acid [oxidising agent] half eqtn shown below The acid is required to provide the hydrogen ions that will eventually form water so 4O needs 8H+
MnO4- + 8H+ + 5e- --> Mn2+ + 4H2O
The iodide reaction
2I- -2e- --> I2

to get the overall reaction, the electrons must balance, so they disappear in the final version. So smallest number containing 5 and 2 is 10. So multiply first eqtn by 2 and second one by 5 and add them.

2MnO4- + 16H+ + 10I- -->2Mn2+ + 8H2O + 5I2