List the 2 major groups of biogenic sedimentary rocks based on their compositions.

Biogenic sedimentary rocks are formed by the remains of the animals and plants via the biological process.

The two major groups are as follows -

Limestone - lt is made up of the exoskeletons of the mollusk, reef-forming corals, and foraminiferans.

Coal - it is made from the carbon in the dead and buried organic material and the wood of the dead plants which do not decay (due to lack of oxygen) but get petrified over the time.