Vanillin,a compound obtained from vanilla beans,has a total sum of oxygen atoms and $\pi$-electrons equal to . . .

Two unknown compounds $X$ and $Y$,both having molecular formula $C_4H_8O$,give the following results with four chemical tests.

Compound	Bromine	$Na$ metal	Chromic acid	Lucas reagent
$X$	decolourises	bubbles	Orange to Green	No reaction
$Y$	No reaction	No reaction	No reaction	No reaction

Compound $X$ and $Y$ respectively are:

The exact order of acidity of the compounds $p-$nitrophenol, acetic acid, acetylene and ethanol is

Identify the correct order of enol content.

The number of $\sigma$ and $\pi$ bonds in propane$-1, 2, 3-$tricarboxylic acid is:

State True or False for the following statements:
$(i)$ Organic compound was first synthesized by $F$. Wohler.
$(ii)$ Berzelius stated that some mysterious force exists in living organisms.
$(iii)$ In $1828$,Wohler prepared an organic compound from an inorganic compound,at which time the vital force theory was accepted.
$(iv)$ Kolbe prepared acetic acid and Berthelot prepared methane.