Answer: volume
Step-by-step explanation:
Horsepower is defined as the unit of measurement of the rate at which work is done.
Mass is defined as the amount of matter contained in the body. It is measured in units like gram(g), kilogram (kg) and milligram (mg).
Volume of the gas is defined as the space occupied by a substance. It is expressed in units like
,
, Liters (L) and milliliters (ml)
Pressure of the gas is defined as the force exerted by the particles on the walls of the container. It is expressed in various terms like 'mmHg', 'atm', 'kiloPascals' etc.