If all of the carbon atoms are linked by single covalent bonds and there are no branches, the compounds are

If all of the carbon atoms are linked by single covalent bonds and there are no branches, the compounds are called homologous series.

Explanation:

A series of carbon atoms which include different number of carbon atoms but have same functional group are known as homologous series.

Generally, these type of series have a chemical formula as .

No branches are present in this type of series.

For example, , , etc are all homologous series.

Thus, we can conclude that if all of the carbon atoms are linked by single covalent bonds and there are no branches, the compounds are called homologous series.

4d^55s^1 ( third choice)