(N/A) Carboxylic acids act as Bronsted acids because they can donate a proton $(H^+)$. Their acidic nature is proven by the following reactions:
$(i)$ Reaction with metals: Carboxylic acids react with electropositive metals like $Na$ and $K$ to liberate dihydrogen gas,acting as proton donors.
$2 RCOOH + 2 Na \longrightarrow 2 RCOO^- Na^+ + H_2 \uparrow$
$(ii)$ Reaction with carbonates and bicarbonates: Carboxylic acids react with mild bases like aqueous solutions of carbonates and hydrogen carbonates to evolve carbon dioxide gas.
$RCOOH + NaHCO_{3(aq)} \longrightarrow RCOO^- Na^+ + H_2O + CO_2 \uparrow$
$2 RCOOH + Na_2CO_3 \longrightarrow 2 RCOO^- Na^+ + H_2O + CO_2 \uparrow$