Answer :

Final answer:

Based on the phase diagram of water, at 186 °C and 1.0 atm pressure, water is in the gas phase, often referred to as steam.

Explanation:

The determination of the phase of a substance at a particular temperature and pressure can be achieved by referencing a phase diagram. In this case, the substance is presumably water as it is the most common substance in reference to these conditions. The phase of water at 186 °C and 1.0 atm pressure can be found using the phase diagram for water.

According to the phase diagram of water, at standard atmospheric pressure of 1.0 atm, water transitions from a liquid phase to a gas phase at 100 °C. Therefore, water at 186 °C and 1.0 atm would be in the gas phase, often referred to as steam.

Understanding a phase diagram can help us predict the state of matter under different thermal (temperature) and barometric (atm, a measure of pressure) conditions. In this case, knowing the conditions allows us to see that at 1.0 atm and 186 °C, water will be in the form of steam, or a gas.

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