Silver halides are used in photography because:

Among the following oxides of $3d$ elements,the number of mixed oxides are . . . . . .
$Ti_{2}O_{3}, V_{2}O_{4}, Cr_{2}O_{3}, Mn_{3}O_{4}, Fe_{3}O_{4}, Fe_{2}O_{3}, Co_{3}O_{4}$

Determine the correct $(T)$ and incorrect $(F)$ statements from the following:
$(a)$ In the titration of $C_2O_4^{2-}$ with $KMnO_4$,$C_2O_4^{2-}$ acts as an oxidizing agent.
$(b)$ $KMnO_4$ is a strong oxidizing agent.
$(c)$ In $Cr_2O_4^{2-}$,the $O-Cr-O$ bond angle is $120^o$.
$(d)$ The standard electrode potential for the reaction $Cr_2O_7^{2-} + 14H^+ + 6e^- \to 2Cr^{3+} + 7H_2O$ is $E^o = -1.33 \ V$.

Select the salt whose aqueous solution is not green.

$NaCl$ reacts with conc. $H_2SO_4$ and $K_2Cr_2O_7$ to give reddish fumes $(B)$,which react with $NaOH$ to give yellow solution $(C)$. $(B)$ and $(C)$ respectively are:

Stainless steel is non-corrosive. This character is more prominent in