Which polymer is used in controlled-release drug capsules?

Which of the following monomers is used in the synthesis of polythene?

Which of the following is not a straight chain hydrocarbon?

Which functional group is present in methyl ethanoate?

The class of organic compounds which gives effervescence with $NaHCO_3$ solution is:

An aldehyde as well as a ketone can be represented by the same molecular formula,say $C_{3}H_{6}O$. Write their structures and name them. State the relation between the two in the language of science.