What are characteristics of a gas?
A) A state of matter that has free electrons
B) A state of matter that conducts electricity well.
C) A state of matter that has both fixed volume and shape.
D) A state of matter that does not have a definite volume or shape.
E) A state of matter that has a definite volume but not a definite shape.

Hint: Matter has three states: solid, liquid, and gas. In a gaseous state, gas particles have weak intermolecular forces of attraction or repulsion. Therefore gas particles have high velocity. Similarly, they do have large intermolecular spaces between them. This allows them to fit in all sizes and shapes of containers.

Complete answer:
Gas is a state of matter. They have a lower density. Gases particles can be easily compressed.
Properties of gas are as follows,
1. Gases do not have a definite shape or volume. They occupy the shape of the container which is accessible to them. Properties of gas are that they fill the volume of the container because the gas particles have a weak or negligible force of attraction between them. This allows them to move randomly in space. They have higher kinetic energy and thus have high velocity.
2. Gases have a property to conduct electricity as all states of matter do. However, they conduct electricity to a lesser extent thus they are considered the poor conductor of electricity. Thus gases are insulators. To conduct electricity a material must have free electrons. These are the electrons that are ready to move and on the application of the electric field they move towards the positively charged terminal.in the gas state, they do not contain the free electrons. Thus cannot conduct electricity. Therefore gas is a state of matter that does not have definite volume and shape and does not conduct electricity.

Hence, (D) is the correct option.

Additional information:
Some of the other properties of gases are:
3) Compressibility: Gases have large intermolecular spaces.by the application of external pressure the spaces between the particles can be reduced and particles are forced to come closer. This is the compressibility of the gas. Thus gases have high compressibility.
4) Diffusion: Gas particles have high velocity. They are large intermolecular spaces between the gas particles. When we mix two gases, the particles of one gas pass through the empty spaces of the other gas. This results in a homogeneous mixture of gases. Thus gases are diffusible.

Note: Free electrons can be produced by the ionization of gas (known as plasma state). Such charged gases are good conductors of electricity.in atmosphere, lightning is a process through which non conducting air ionizes and conducts electricity.