Question

Four students added a small amount of ethanoic acid to sodium hydrogencarbonate. The gas evolved was tested for its behaviour with burning splinter and lime water. They reported their observations as given below.

Student	Gas evolved	Action on burning splinter	Action on lime water
A	CO2	The flame of splinter extinguishes and gas does not burn	Turned milky
B	SO2	The splinter burns brightly and the gas burns with a pop	Turned green
C	NO2	The gas does not burn but the splinter burns with a hissing sound	Turned black
D	O2	The gas burns with a yellow flame and the splinter extinguishes	Turned purple

The correct observations have been reported by student:
(1) A
(2) B
(3) C
(4) D

Answer 1

When ethanoic acid is treated with sodium hydrogen carbonate, it will give sodium carboxylate salt, carbon dioxide, and water. Evolved carbon dioxide forms carbonate products which turns lime water milky.
${\mathrm{CH}}_3\mathrm{COOH}\left(\mathrm{aq}\right)+{\mathrm{NaHCO}}_3\left(\mathrm{s}\right)\to {\mathrm{CH}}_3\mathrm{COONa}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

Hence, the correct answer is option 1.