The temperature at which a liquid changes to a gas is best described as

Answer: A — Boiling Point

The boiling point is the temperature at which a liquid changes to a gas. At this point, the liquid’s vapor pressure equals the surrounding atmospheric pressure, allowing bubbles of vapor to form inside the liquid and rise to the surface. Below this temperature, evaporation can occur at the surface but the liquid doesn’t boil. The other terms refer to different ideas: vapor pressure is the pressure that vapor in equilibrium with the liquid exerts at a given temperature; melting point is the temperature where a solid becomes a liquid; and flash point is the lowest temperature at which a liquid can produce enough vapor to ignite in the presence of an ignition source, not the temperature at which it becomes a gas.