What summarises the relationship between steam and water volume?

The correct answer highlights that steam expands significantly from water. This is a fundamental concept in thermodynamics and relates to how water transitions to steam. When water is heated and transforms into steam, its volume increases dramatically—by about 1,600 times at standard atmospheric pressure. This occurs because the molecules in steam are in a gaseous state, moving freely and occupying a much larger volume compared to the liquid state of water, where molecules are more closely packed together.

This significant volume change is essential in applications such as steam engines and other heat exchange systems, where steam is utilized to do work or transfer heat. Understanding this expansion is crucial for those working with steam systems to account for pressure, temperature, and volume changes in practical scenarios.

While other options touch on aspects related to steam and water, they do not capture the magnitude and significance of the volume expansion in steam compared to water. For instance, steam's volume being equal to that of water would misrepresent the behavior of water as it vaporizes. Similarly, while atmospheric pressure does influences steam's volume, the core concept of its expansion relative to water is the primary focus here.