Which type of isomerism is shown by propanal and propanone?

$(A) CH_3-CH_2-CH_2-CO_2H$ and $(B) CH_3-CH(CO_2H)-CH_3$ are:

For which of the following factors can the structural isomers $C_2H_5OH$ and $CH_3OCH_3$ be assumed to have the same value? (Assuming ideal behavior)

Isopentane and neopentane exhibit which type of isomerism?

Which one of the following compounds is not an isomer of the others?

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?