Heat oven to 350°F. Grease 13x9-inch (3-quart) baking dish. Pour uncooked rice over bottom of greased dish. Sprinkle evenly with seasoning mix packet. Arrange chicken pieces over rice. Spoon celery and mushrooms around chicken.
In medium saucepan, combine water and soup; mix well. Bring to a boil. Pour evenly over chicken and vegetables. Sprinkle chicken with paprika. Cover with foil.
Bake at 350°F. for 1 hour. Uncover; bake an additional 20 to 30 minutes or until chicken is fork-tender and juices run clear. Let stand 5 minutes before serving.