The carbon atom is sometimes listed as carbon-12 and sometimes as carbon-14 what does this mean? plz this is urgent

Carbon-12 has 6 neutrons and 6 protons, making it 12.
Carbon-14 has 8 neutrons and 6 protons, making it 14.
It is used to date the age of things that are very old using radioactive isotopes.

Wetlands form where water and land meet. a lake with a wetland fringe can fill in with decayed plant and animal material to become a wet meadow. a pond can fill in to become a bog or fen. sediment can fill in a river marsh to become a swamp.flooding of coastal lowlands from rising sea levels has created broad coastal marshes that are protected from wave action by barrier islands or reefs. coastal wetlands also form when rivers deposit sediment as they reach the ocean. plants then take root and hold the soil firm against the forces of tides and waves.

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