Total number of isomers of $C_6H_{14}$ are

In which structure is the central carbon $(C-3)$ not a chiral centre?

Identify the correct statement among the following:

Among the following,identify the compound that is not an isomer of hexane $(C_6H_{14})$:

For which of the following parameters would the structural isomers $C_2H_5OH$ and $CH_3OCH_3$ be expected to have the same values? (Assume ideal behavior)

Tautomerism is exhibited by