Which structural formula does not represent benzene? a hexagon with nothing drawn inside it a hexagon with a dotted circle drawn inside it a hexagon with single and double dashes on alternating sides a hexagon with a circle drawn inside it?

            A hexagon with nothing drawn inside it does not represent Benzene.

Explanation:

Below attached picture contains structures mentioned in given option.

Structure of Option-A is shown in Red Color.

Structure of Option-B is shown in Blue Color.

Structure of Option-C is shown in Green Color.

Structure of Option-D is shown in Orange Color.

Result:
          Except Option-A, all structures represent Benzene. Option-A in fact shows the structure of Cyclohexane.

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water