Final answer:
One assumption made by treating a gas as ideal is that the gas molecules have negligible volume and negligible intermolecular interactions. If this assumption turns out to be true, the consequences are that the ideal gas law can accurately describe the gas's behavior.
Step-by-step explanation:
An assumption made by treating a gas as ideal is that the gas molecules have negligible volume and that intermolecular interactions are negligible. This means that the gas molecules themselves do not occupy an appreciable part of the whole volume and do not have attractive forces between them. If this assumption turns out to be true, the consequences are that the ideal gas law can accurately describe the behavior of the gas and predictions made using the ideal gas law will be close to the observed behavior of the gas.