The number of isomers of $C_4H_{10}$ is:

Which of the following is not an isomer of pentane?

Which of the following will show tautomerism?

Which of the following methods of structural formula representation conventionally uses a point for the front carbon and a circle around it for the rear carbon?

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

How many of the following compounds show the phenomenon of tautomerism?