The compound that does not liberate CO2 on treatment with aqueous sodium bicarbonate solution, is: benzoic acid, salicylic acid, carbolic acid (phenol), benzenesulphonic acid

Benzoic acid and benzene sulphonic acid are stronger acids so liberate CO2. pKa of PhOH (carbolic acid) is 9.98 and that of carbonic acid (H2CO3) is 6.63 thus phenol does not give effervescence with HCO₃⁻ ion. Hence, answer is option A (carbolic acid (phenol)).