Carbon can form both polar and nonpolar covalent bonds. The type of bond depends on the electronegativity of the atoms involved. Nonpolar covalent bonds are formed when two atoms have similar electronegativities, such as carbon-carbon bonds. Polar covalent bonds are formed when the difference in electronegativity is greater than 0.4 but less than 1.7, such as a carbon-oxygen bond.

Here are some examples of carbon-based molecules and the types of bonds they form:

- Methane (CH4): Carbon forms four nonpolar covalent bonds with four hydrogen atoms.

- Carbon dioxide (CO2): Carbon forms two polar covalent bonds with two oxygen atoms.

- Ethanol (C2H5OH): Carbon forms three nonpolar covalent bonds with three hydrogen atoms and one polar covalent bond with one oxygen atom.

- Acetone (CH3COCH3): Carbon forms three nonpolar covalent bonds with three hydrogen atoms, two polar covalent bonds with two oxygen atoms, and one covalent bond with another carbon atom.