Standard air is
a) the volume of 1 kg of air at 15 degrees Celsius and 100 kpa
b) the mass of 1 cubic metre of air at atmospheric conditions
c) the volume of 1 kg of air at ambient temperature and atmospheric pressure
d) the volume occupied by 1 kg of dry air at 21 degrees Celsius and atmospheric pressure at sea level or 101.325 kpa
e) the mass of 1 cubic metre of dry air at 20 degrees Celsius and atmospheric pressure
Answer: D