Which of the following is a characteristic of steam?

Steam is characterized by the fact that it occupies more space, or has a larger volume, compared to the same mass of liquid water. When water converts to steam, it expands drastically due to the high energy of the molecules. This property is crucial in various applications, especially in generating power where steam is used to drive turbines.

The correct choice reflects this characteristic of steam. The physical properties of steam and its behavior in different scenarios, such as in engines and heating systems, highlight why it is essential to understand how steam behaves in relation to water.

The other options do not accurately describe steam. For example, steam actually has a lower density compared to water. Additionally, at standard atmospheric pressure, steam exists as a gas, and not in liquid form. Finally, steam can indeed affect temperature; it can transfer heat effectively, which is a fundamental principle of how boilers and heat exchangers operate. Understanding these properties is vital for anyone preparing for a position involving steam engineering or management.