Which of the following are true statements?
O Hydrofluorocarbons do not affect the ozone layer.
O Alkenes, alkynes and aromatics are all examples of saturated compounds.
O The alkyl group known as the propyl group is CH₃CH₂CH₂⁻.
O Cis-trans isomers can occur with an open chain alkane.
O A hydrocarbon burns in air to produce carbon dioxide and water.
