A scientist is examining a mixture of nitrogen, hydrogen, and ammonia. The individual pressures that are exerted by nitrogen and hydrogen are 0. 26 atm and 0. 28 atm, respectively. If the total pressure is 0. 90 atm, what is the partial pressure of ammonia? Use P subscript T equals P subscript 1 plus P subscript 2 plus P subscript 3 plus ellipses plus P subscript n. 0. 27 atm 0. 36 atm 0. 54 atm 0. 90 atm.