Final answer:
To use Charles's law, the pressure and amount of gas must remain constant while the volume changes proportionally to the absolute temperature measured in Kelvin. Option 3
Step-by-step explanation:
To apply Charles's law, which relates the volume and temperature of a gas, certain conditions must remain constant. These conditions are the pressure of the gas and the amount of the gas (usually measured in moles). This means that while the volume and temperature of the gas sample can change, the amount of gas and the pressure it is under should not change for Charles's law to be valid.
Charles's law states that for a given mass of gas at constant pressure, the volume is directly proportional to its absolute temperature (measured in Kelvin). Therefore, any analysis involving Charles's law requires the temperature to be in Kelvin to acknowledge the absolute zero as a starting point where molecular motion ceases. Option 3