Hey student,

Chemosynthetic Organisms are those organisms which obtain their food using the chemical energy present in inorganic molecule.

Chemosynthetic autotrophic are those organisms which use inorganic substrates as energy source and CO2 as carbon source and synthesize their own food and doesn't depend on other organisms for food. In simpler words, an autotroph that is capable of synthesizing complex organic materials from inorganic reactions.

I hope it helps.