How many carbon atoms are present in ethane?

Ethane is a simple alkane with the chemical formula C₂H₆. The formula indicates that for every two hydrogen atoms, there are two carbon atoms. The "C" stands for carbon, and the subscript "2" after the "C" specifies that there are two carbon atoms present in the molecule. In terms of structure, ethane consists of a chain of two carbon atoms bonded to each other, with each carbon atom also bonded to sufficient hydrogen atoms to complete its tetravalent nature (having four bonds). Therefore, the presence of two carbon atoms is the defining feature of ethane, which aligns with the correct answer.