Carbon and oxygen Isotopes are the two atoms present in shells of single-celled plankton that sank to the bottom of the ocean.
Composition of shell
The shells of single celled plankton is made up of calcium carbonate or from tiny grains of sand stuck together. Mostly, they are made of calcium carbonate and we know that carbonate is formed from one carbon atom and three oxygen atom.
So we can conclude that carbon and oxygen Isotopes are the two atoms present in shells of single-celled plankton that sank to the bottom of the ocean.
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