The properties of acetic acid were studied by a student by conducting an experiment. Answer the following questions: 

(i) Which substance he must add to acetic acid to produce carbon dioxide? 

(ii) Mention the chemical reaction taking place. 

(iii) How would he test 𝐶𝑂₂ gas in the laboratory?

(i) The substance he must add to acetic acid is sodium carbonate $\left(N{a}_{2}C{O}_3\right)$ and sodium hydrogen carbonate $\left(NaHC{O}_3\right)$ to produce carbon dioxide.
(ii) The chemical reaction is as follows:

$2C{H}_{3}COOH+N{a}_{2}C{O}_3\to 2C{H}_{3}COONa+H_{2}O+C{O}_2$

$C{H}_{3}COOH+NaHC{O}_3\to C{H}_{3}COONa+H_{2}O+C{O}_2$

(iii) The test to identify carbon dioxide gas is a lime water test. Liberated $C{O}_2$ passes through lime water which turns it milky.