Step 1: Understanding the Question.
Ethanol vapour is passed over copper at 573 K. We must pick the organic product from four carbonyl compounds.
Step 2: Use the carbon count.
In this reaction the carbon skeleton does not change. Only hydrogen is removed.
Ethanol has 2 carbons, so the product must also have 2 carbons.
Option (2) has 3 carbons, option (3) has 1 carbon, and option (4) has 3 carbons. Only option (1) has 2 carbons.
Step 3: Confirm by the hydrogen count.
Ethanol is C$_2$H$_6$O. Losing one H$_2$ gives C$_2$H$_4$O.
Ethanal, CH$_3$CHO, is C$_2$H$_4$O. So the formula also fits option (1).
Step 4: Confirm the functional group.
The carbon bearing OH in ethanol has two hydrogens. One H leaves from this carbon and one from the OH group. The carbon is left with a double bond to oxygen and one H, which is an aldehyde group.
Final Answer:
The product is ethanal, option (1).
\[ \boxed{\text{Option (1)}} \]
