Final answer:
LP-gas capacity must indeed be marked on a DOT cylinder, which informs users of the cylinder's storage capacity. Reading the gauge for remaining gas requires consideration of ambient temperature due to Gay-Lussac's Law.
Step-by-step explanation:
Yes, LP-gas capacity must be marked on a DOT cylinder. This is a requirement by law to ensure safety and to provide users with clear information on the storage capacity of the cylinder. The capacity is often marked in gallons or pounds of propane.
When using propane tanks, especially for activities like grilling, it's important to know how much gas you have to avoid running out unexpectedly. A gas gauge can help determine how much gas is left, but remember that the pressure readings can be affected by ambient temperature, as stated by Gay-Lussac's Law. This law indicates that the pressure of a gas is directly proportional to its absolute temperature when volume is held constant, which means pressure can fluctuate with temperature changes. Therefore, you must consider the current air temperature to accurately interpret the gauge's pressure reading when determining how much gas remains in the tank.