20. a) Draw geometrical isomers of butene. Also, write two conditions for geometrical isomerism (3.0 marks).
b) Explain boiling point and physical states of alkane. (2.0 marks)
Draw three isomers for a chloroalkane having 4 carbons and identify them as primary, secondary, and tertiary alkyl halides. Explain the SN2 mechanism for the reaction of one of the isomers with KOH (5.0 marks).