(a)[1]
Show the structures of a pair of positional isomers with formula $\text{C}_4\text{H}_8$.
(b)[1]
Show the structures of a pair of chain isomers with formula $\text{C}_4\text{H}_8$ that do not show stereoisomerism.
(c)[2]
Show the structures and full names of a pair of stereoisomers with formula $\text{C}_4\text{H}_8$.
(d)[3]
The structure of a molecule, A, with formula $\text{C}_4\text{H}_8$ is shown. Draw a functional group isomer of molecule A in box B. Explain how molecules A and B could be told apart using a chemical test.