A 60.0-g sample of fermium-253 was placed in a sealed vessel 9.0 days ago. Only 7.5 g of this isotope is now left. What is the half-life of fermium-253? 3.0 days 4.5 days 17.5 days 20.0 days change to the reactants would accomplish this? Increase the volume to decrease pressure and to increase concentration. Increase the volume to increase pressure and to decrease concentration. O Decrease the volume to decrease pressure and to increase concentration. O Decrease the volume to increase pressure and to increase concentration.