Answer: The elements which are common for all organic molecules is hydrogen and carbon.
Step-by-step explanation:
Another name for organic molecules are hydrocarbons. This means that the molecules which consist of hydrogen and carbon atoms is an organic compound.
For Example:
are not organic compounds, because in water, carbon is not there and in carbon dioxide, hydrogen is not there. But,
is an organic compound because hydrogen and carbon both are present.
Hence, hydrogen and carbon elements are common to all organic molecules.