Question

Which yields H+(aq) as the only positive ion in an aqueous solution?(1) CH3CHO (2) CH3CH2OH (3) CH3COOH (4) CH3OCH3

Answer 1

If H+ would have to dissociate from a substance and must be the only positive ion in the solution that substance must be an acid.
CH3CHO is an aldehyde called acetaldehyde. 
CH3CH2OH is an alcohol called ethanol 
CH3OCH3 is an ether called dimethyl ether. 
and finally, the answer CH3COOH is a weak acid called acetic acid. 

Answer 2

Answer:The correct answer is option (3).

Explanation:

Carboxylic acid gives $H^+$ ions in their aqueous solution.

$RCOOH\rightleftharpoons RCOO^-+H^+$

$CH_3COOH\rightleftharpoons CH_3COO^-+H^+$

Carbonate ion formed is stabilized due to resonance.

Whereas aldehyde in their aqueous solution do not give $H^+$ions.

Alcohol in their aqueous solution do not give $H^+$ions.

Ether in their aqueous solution do not give $H^+$ions.