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

Which of the following has the maximum enol content?

Glycerol is not used in which of the following cases?

Which compound contains $1^o, 2^o, 3^o$ and $4^o$ carbon atoms?

Given below are two statements:
Statement-$I$ : Compound $(X)$,shown below,dissolves in $NaHCO_3$ solution and has two chiral carbon atoms.
Statement-$II$ : Compound $(Y)$,shown below,has two carbons with $sp^3$ hybridization,one carbon with $sp^2$ and one carbon with $sp$ hybridization.
In the light of the above statements,choose the correct answer from the options given below:

Which of the following will have the highest enol content?