Number of structural isomers of ${\mathrm{C}}_3{\mathrm{H}}_9\mathrm{N}$ are

Write the structural formula corresponding to the enol form of $2,4-\mathrm{dimethyl}-3-\mathrm{pentanone}.$

Write the structural formula corresponding to the enol form of acetone.

Write the structural formula corresponding to:

The two enol forms of $2-\mathrm{methylcyclohexanone}.$

Write the structural formula corresponding to:

The two most stable enol forms of    

Write the structural formula corresponding to:

The two most stable enol forms of $1-\mathrm{phenyl}-1, 3-\mathrm{butanedione}.$

Write the structure of a tautomeric isomer for the following compounds:

Write the structure of a tautomeric isomer for each of the following compounds:

Write the structure of a tautomeric isomer for the following compounds: