At $pH = 12$,what change occurs in $Cr_2O_7^{2-}$?

When $Cu^{2+}$ ion is treated with $KI$,a white precipitate is formed. Explain the reaction with the help of a chemical equation.

Assertion $(A)$: $CuI_2$ cannot be prepared by the reaction of $Cu^{2+}_{(aq)}$ with $I^{-}_{(aq)}$.
Reason $(R)$: Aqueous $Cu^{2+}$ solution is blue in colour.
The correct answer is:

Arrange the oxides $CrO$,$CrO_3$,and $Cr_2O_3$ in the decreasing order of acidic strength.

$E^{\circ}_{M^{3+} \mid M^{2+}} \text{ (in } V\text{) is highest for}$

Which of the following metals becomes passive when treated with concentrated $HNO_3$?