Find the main product of the following reaction:

Which acid will not form a hydrocarbon upon decarboxylation?

What is the percentage of acetic acid present in vinegar?

How many of the following compounds react with $NaHCO_3$ to evolve $CO_2$ gas?
$I$: $3$-Nitrophenol
$II$: $2,4$-Dinitrophenol
$III$: $4$-Hydroxybenzoic acid
$IV$: $4$-Methylbenzoic acid
$V$: $4$-Chlorophenol
$VI$: $2,4$-Dinitrotoluene
$VII$: $4$-Hydroxybenzenesulfonic acid
$VIII$: $4$-Sulfobenzoic acid
$IX$: Squaric acid
$X$: Maleic acid

Assertion $: - >C=O$ group is present in both aldehydes and acid derivatives.
Reason $: -$ Aldehydes give nucleophilic addition across $>C=O$ bond but acid derivatives do not exhibit such reactions.

$RCOOH + NaHCO_3 \to RCOONa + H_2O + CO_2$. In this reaction,the $CO_2$ evolved comes from: