feet; abbreviation: ft; symbol: â² , the prime symbol) is a unit of length in the imperial and US customary systems of measurement. Since 1959, both units have been defined by international agreement as equivalent to 0.3048 meters exactly. In both systems, the foot comprises 12 inches and three feet compose a yard.
Avogadro's law (sometimes referred to as Avogadro's hypothesis or Avogadro's principle) is an experimental gas law relating volume of a gas to the amount of substance of gas present.[1] A modern statement of Avogadro's law is:
Or to put it another way the principle that equal volumes of all gases at the same temperature and pressure contain the same number of molecules. Avogadro's number is one of the fundamental constants of chemistry. It permits calculation of the amount of pure substance (mole), the basis of stoichiometric relationships.