When an excess of $KI$ is added to a $CuSO_4$ solution and then $Na_2S_2O_3$ is added to the mixture,which of the following statements is incorrect?

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

Given below are two statements:
Assertion $(A)$: All $Cu$ $(II)$ halides are known except the iodide.
Reason $(R)$: $Cu^{2+}$ oxidizes $I^{-}$ to $I_2$.
The correct answer is:

For which of the following is the $E^{\ominus}(M^{3+} / M^{2+})$ value negative?

Given below are two statements for catalytic properties of transition metals. Statement $I$: First row transition metals which act as catalyst utilise their $3d$ electrons only for formation of bonds between reactant molecules and atoms on the surface of catalyst. Statement $II$: There is increase in the concentration of reactants on the surface of catalyst which strengthens the bonds in reacting molecules. In the light of the above statements, choose the correct answer from the options given below:

Which of the following is the correct order of acidic character?