Question

at 20 C the vapor pressure of dry ice is 56.5 atm. if 32 g of dry ice is placed in an evacuated .25 l chamber at a constant temperature of 20 C will all the dry ice sublime

Answer 1

No. Use PV = nRT. You know n, R, T and V, solve for P. If P is > 56.5 all will not sublime. If P<56.5, all of it will sublime.