Describe the characteristic infrared absorption frequencies that would allow you to distinguish between the following pairs of compounds.

a) 2,3-dimethylbut-2-ene and 2.3-dimethylbut-1-ene

b) cyclohexa-1,3-diene and cyclohexa-1,4-diene

c) pentanal and pentan-2-one

d) butanamide and pentan-3-one

e) oct-1-yne and octanenitrile

f) butanoic acid and 3-hydroxybutanal

g) cyclohexanol and cyclohexanone

h) cyclohex-2-enone and cyclohex-3-enone