Question

An organic compound 'A' produces a gas with brisk effervescence when sodium bicarbonate is added to it. The compound 'A' contains the same number of carbons as in ethane. The compound 'A' reacts with ethanol to form a sweet-smelling compound 'C' in presence of conc. ${H_{{2^{}}}}S{O_4}$acid. Then the name of compound A and the gas evolved is
A.Ethanoic acid, $C{O_2}$
B.Methanoic acid,$C{O_2}$
C.Ethanoic acid, ${H_2}$
D.Methanoic acid, ${H_2}$

Answer 1

Carboxylic acid with sodium bicarbonate produces carbon dioxide which produces effervescence. And we know that esters are sweet smelling compounds formed by reaction of alcohol with carboxylic acid in presence of ${H_2}S{O_4}$.

Complete answer:
Now, understanding the question with the help of step by step process and studying the hints to obtain compound A along with the gas evolved.
As given compound A has the same number of carbon atoms as in ethane that means compound A contains two carbon atoms.
Here in the question we have been provided with an organic compound ‘A’ which when reacts with another compound sodium bicarbonate produces a gas with brisk effervescence. Also, when sodium bicarbonate reacts with an acid it produces carbon dioxide with brisk effervescence. From here we came to know that the gas produced in the reaction is carbon dioxide ($C{O_2}$) and since compound ‘A’ is an organic compound, it should be a carboxylic acid.
In the question it is given that compound ‘A’ reacts with ethanol to form a sweet-smelling compound ‘C’ in the presence of concentrated ${H_{{2^{}}}}S{O_4}$ acid. This reaction is known as esterification reaction and therefore compound ‘C’ is ethyl ethanoate as ethanoic acid reacts with ethanol in the presence of conc. ${H_{{2^{}}}}S{O_4}$to give ethyl ethanoate.
The reaction is as follow
$C{H_3}COOH + NaHC{O_3} \to C{H_3}COONa + C{O_2} + {H_2}O$
And reaction of A with ethanol is
$C{H_3}COOH + {C_2}{H_5}OH\xrightarrow{{Conc.{H_2}S{O_4}}}C{H_3}COOC{H_{_2}}C{H_3} + {H_2}O$
Therefore compound ‘A’ is ethanoic acid and the gas produced is carbon dioxide.

Hence, the correct option is option ( A ).

Note:
Sweet smelling compounds are esters which are used in perfume in the perfume industry and the process of formation of ester is known as esterification.
Whenever a compound reacts with sodium bicarbonate and produces brisk effervescence this is evidence that carbon dioxide is liberated.