Commensalism is when one organism benefits off the other one without harming it. Examples are tree frogs that use plants for protection or jackals that have been expelled from packs trailing tigers and feeding on the remains of its kill. Barnacles on whales get shelter by attaching to a whales body
Hydrogen as in hydrocarbons
nitrogen as in cyanides
sulphur as in carbon di sulphides
oxygen as in combustion of carbon
the rest i left out needs a third party element to bond to carbon
