Option A CrO is basic but Cr2O3 is amphoteric. Cr oxidation states: In CrO,Cr is in +2 oxidation state → basic oxide. In Cr2O3, Cr is in +3 oxidation state ⟶ amphoteric oxide. This statement is correct. Option B Nitrite is oxidised to nitrate in acidic medium by KMnO4. In acidic medium, MnO4−⟶Mn2+ (oxidizing agent). Nitrite ( NO2−,N in +3 ) can be oxidized to nitrate ( NO3−,N in +5 )). This is correct. Option C PdCl2 is the catalyst in Wacker process. The Wacker process (oxidation of ethylene to acetaldehyde) uses PdCl2−CuCl2 as a catalyst system. Correct. Option D The reactivity of the earlier members of lanthanide series is similar to that of aluminium. Lanthanides are strongly electropositive and more reactive than aluminum. They readily react with water and acids even at moderate temperatures, unlike AI (which is passivated by oxide film). This statement is not correct.