How much greater is the volume of water vapor compared to an equal amount of liquid water?

The correct choice indicates that the volume of water vapor is approximately 1700 times greater than the equivalent volume of liquid water. This significant difference in volume can be attributed to the molecular structure and behavior of water in its gaseous state compared to its liquid state.

In the liquid state, water molecules are closely packed together due to intermolecular forces, primarily hydrogen bonding. These forces hold the molecules relatively close, resulting in a high density and a smaller volume for a given mass of liquid water.

When water is converted to vapor, the molecules gain kinetic energy, which causes them to move apart significantly. In the gaseous state, the molecules are far less densely packed, allowing for much more space to be occupied. This expansion results in a dramatic increase in volume.

Thus, when considering an equal mass of liquid water versus water vapor, the vapor's volume is indeed around 1700 times larger due to these physical properties and the resultant behavior of water molecules in different states.