The total number of structural isomers of $C_3H_6O$ is:

Explain the following terms:
$(a)$ Isomerism
$(b)$ Position isomerism
$(c)$ Chain isomerism
$(d)$ Functional group isomerism
$(e)$ Metamerism
$(f)$ Optical isomerism

The isomerism exhibited by alkyl cyanide $(R-CN)$ and alkyl isocyanide $(R-NC)$ is:

Assertion $A$: Enol form of acetone $[CH_{3}COCH_{3}]$ exists in $< 0.1 \%$ quantity. However,the enol form of acetylacetone $[CH_{3}COCH_{2}COCH_{3}]$ exists in approximately $15 \%$ quantity.
Reason $R$: Enol form of acetylacetone is stabilized by intramolecular hydrogen bonding,which is not possible in the enol form of acetone. Choose the correct statement:

What is structural isomerism? Give two examples of chain isomerism in alkanes. Or,explain the isomerism of alkanes having more than three carbon atoms using two examples.

How many structural isomers are possible for a compound with molecular formula $C_3H_7Cl$?