Anitrogen atom has 7 protons, and the most common isotope of nitrogen has 7 neutrons. a radioactive isotope has 9 neutrons. what are the atomic numbers and mass numbers of the stable and radioactive forms of nitrogen?

During an experiment, readings for blood pressure in a persons body were found to be constant . however , when he measured by a different blood pressure cuff , the readings differed by 15 points for each reading. this difference indicates that the results are