A compound A `(C_(2)H_(4)O_(2))` reacts with Na metal to form a compound 'B' and evolves a gas which burns with a pop sound. Compound 'A' on treatment with an alcohol 'C' in the presence of an acid forms a sweety smelling compound 'D' `(C_(4)H_(8)O_(2))`. On addition of naoH to 'D' gives back B and C. Identify A,B,C and D. Write the reaction involved.
OR
(a) Explain why carbon forms covalent bond? Give two reasons for carbon forming a large number of compounds.
(b) Explain the structure of ammonia molecule.

Explanation

The available information suggests that the compound 'A' is ethanoic acid, the compound 'B' is sodium ethanoate and the gas which is evolved and burns with pop sound is hydrogen. The sweet smelling compound 'D' is an ester ethyl ethanoate ad is formd by reacting ethanoic acid (A) with alcohol `C_(2)H_(5)OH` (C). the chemical reactions involved are listed below:
`underset("Ethanoic acid " C_(2)H_(4)O_(2)" "(A))(C_(2)H_(3)COOH)+Natounderset((B)" Sod. ethanoate")(CH_(3)COONa+1//2H_(2))`
`underset("Ethanoic acid")(CH_(3)COOH)+underset("Ethanol (C)")(C_(2)H_(5)OH)overset(H^(+)(acid))tounderset("Ethyl ethanoate "C_(4)H_(8)O_(2)(D))(CH_(3)COOC_(2)H_(5))`
`underset("Ethyl ethanoate")(CH_(3)COOC_(2)H_(5))+NaOHoverset("saponification")tounderset("Sod. ethanoate (B)")(CH_(3)COONa)+underset("Ethanol (C)")(C_(2)H_(5)OH)`
OR
(a) Formation of covalent bond by carbon, .
Carbon forming a large number of compounds, this is because of self linking property of carbon known as catenation.
(b) For the structure of `NH_(3)` molecule.