The correct answer is option 2, Hexane.

A sooty flame is produced when there is incomplete combustion of carbon-containing compounds. Soot consists of unburned carbon particles.

Benzene, option 1, is a carbon compound that can give a sooty flame because it contains carbon and hydrogen atoms, which can undergo combustion.

Hexane, option 2, is also a carbon compound. However, it does not contain any aromatic or conjugated pi bonds, which are known to enhance the production of soot. Therefore, hexane will not produce a sooty flame.

Naphthalene, option 3, is an aromatic hydrocarbon that contains conjugated pi bonds. It can undergo combustion and produce a sooty flame.

Anthracene, option 4, is also an aromatic hydrocarbon with conjugated pi bonds. It can also produce a sooty flame when burned.

In summary, hexane, option 2, is the correct answer because it is a carbon compound that does not contain aromatic or conjugated pi bonds, and therefore, it will not produce a sooty flame.