This is an application of Boyle's law: P₁V₁ = P₂V₂. we don't have to convert volume and pressure to standard forms. we can even use the pressure with mmHg 1 atm = 760 mmHg V₂ = P₁V₁ / P₂ = 745 x 500 / 760 = 490 ml Note that here we assume constant temperature
