The correct option is Temperature and pressure
Explanation
The physical state of a substance (solid, liquid, or gas) is determined by the interplay between
intermolec (which attract particles to one another) and
thermal energy (which encourages particles to move apart). These factors are controlled by external environmental conditions.
Role of Temperature and Pressure
- Temperature: Temperature is a measure of the thermal energy. Increasing the temperature increases the kinetic energy of the particles, allowing them to overcome intermolecular forces. This facilitates transitions from ordered states to disordered states (e.g., solid to liquid, liquid to gas). Conversely, decreasing temperature reduces kinetic energy, favoring the formation of liquids or solids.
- Pressure: Pressure influences the distance between particles. Increasing pressure forces particles closer together, which generally favors the formation of denser states like liquids and solids. Decreasing pressure allows particles to expand, favoring the gaseous state.
Analysis of Incorrect Options
- Mass and density Mass and density: Mass is an intrinsic property that remains constant during physical changes. Density changes as a result of the phase transition but is not the external condition used to trigger it.
- Mass only Mass only: Mass does not determine the phase of a substance; a specific mass of water can exist as ice, liquid water, or steam depending on the conditions.
- Volume only Volume only: Volume is a dependent variable that changes in response to temperature and pressure; it is not the primary control condition for interconversion.
Key Takeaway
The interconversion of states of matter is primarily achieved by altering
temperature (to change kinetic energy) and
pressure (to change inter-particle distance).