The number of structural isomers for $C_6H_{14}$ is

What is isomerism? Explain with a suitable example.

Find out the incorrect relation in the following pair of compounds:

How many positional isomers are possible for the compound $1,1-dideuterocyclohexane$ shown in the image?

Provide the structures of chain isomers of $C_6H_{14}$ that contain two methyl groups,along with their $IUPAC$ names.

The starting material is propene $(CH_3-CH=CH_2)$. The reaction with $H_3O^+$ (acid-catalyzed hydration) follows Markovnikov's rule to give $A$ (propan$-2-$ol,$CH_3-CH(OH)-CH_3$). The reaction with $(i) BH_3/THF$ followed by $(ii) H_2O_2/OH^-$ (hydroboration-oxidation) follows anti-Markovnikov's rule to give $B$ (propan$-1-$ol,$CH_3-CH_2-CH_2OH$). What is the relationship between products $A$ and $B$?