[" 13."[XY_(2)" dissociates as,"],[XY_(2)(g)rightleftharpoons Y(g)+Y(g)],[" Initial pressure of "XY_(2)" is "600mm" of Hg.The total "],[" pressure at equilibrium is "800mm" of Hg.Assuming "],[" volume of system to remain constant,the value of "],[K_(p)" is "],[" (1) "50],[" (3) "20]]