Aldehydes And Ketones

Acidic strength in alcohols depends on the stability of the conjugate base (alkoxide ion). The more stable the alkoxide, the stronger the acid. - (ii) is ethanol (primary) – least hindered, most acidic. - (i) is isopropyl alcohol (secondary) – more hindered, less acidic. - (iii) is tert-butyl alcohol (tertiary) – most hindered, least acidic. Thus, the correct order is:

Carboxylic acids react with NaHCO3} to liberate carbon dioxide gas:
Ar–COOH + NaHCO3} → Ar–COONa + H2}O + CO2}↑
Effervescence of CO2} is a test for carboxylic acids.

The reactivity of carbonyl compounds towards nucleophilic addition depends on the electron withdrawing or donating nature of the substituents.
% Option (a) Benzophenone has two electron-donating phenyl groups — least reactive.
% Option (b) p-Methylbenzaldehyde — methyl is slightly donating.
% Option (c) Benzaldehyde — no additional substituent.
% Option (d) p-Nitrobenzaldehyde — nitro group is strongly withdrawing, making the carbon more electrophilic.
Thus, reactivity order: