Final answer:
Ethanol is oxidized in the reaction with CrO₃ to form ethanal. Correct option is 2.
Step-by-step explanation:
In the reaction between ethanol (C₂H₅OH) and CrO₃, ethanol is oxidized to form ethanal (CH3CHO).
During oxidation, there is a loss of electrons or an increase in the oxidation state of a compound. In this reaction, the carbon atom in ethanol goes from an oxidation state of -2 to +1 in ethanal, indicating an increase in oxidation state and thus, ethanol is oxidized.
Therefore, the answer is 2) oxidized.