A compound C [molecular formula `C_2H_4O_2`] reacts with Na. metal to form a compound R and evolves a gas which burns with pop sound. Compound C on treatment with alcohol A in the presence of an acid forms a sweet-smelling compound S [molecular formula `C_3H_6O_2`]. On addition of NaOH to C, it also gives R and water. S on treatment with NaOH solution gives back Rand A.
Identify C, R, A, and S and write the reactions involved.

Explanation

`C: CH_3COOH. " " R: CH_3COONa.`
`A: CH_3OH. " " S: CH_3COOCH_3`.
Reactions :
`2CH_3COOH + 2Na to 2CH_3COONa + H_2`
`CH_3COOH + CH_3OH overset(H+)(rarr) CH_3COOCH_3 + H_2O`
`CH_3COOH + NaOH to CH_3COONa + H_2O`
`CH_3COOCH_3 + NaOH to CH_3COONa + CH_3OH`
`underset("Acetic acid")(CH_3 -overset(O)overset(||)(C )-OH) + underset("Ethanol")(HO - CH_2CH_3) overset(H^+)( `underset("Ethyl acetate")(CH_3 - overset(O)overset(||)(C )-O -CH_2CH_3) + underset("Water")(H_2O)`.