CHICAGO, Jan, 26.—(UP)—A 14- year-old boy has admitted that he shot and killed his mother because she scolded him for playing hockey, a police official announced. Philip Cammack Jr., said he shot his mother, Mrs. Marie Cammack, 40, while she was bending over a washtub doing the family laundry Wednesday night, Chief Maurice — of the Cook County police said. The boy fired three bullets from a .22 caliber rifle into her head, Green said,