Which of the following processes causes the greatest loss of mass within an atom

If y gets smaller as x gets bigger and y have an relationship?

Achlorine atom has 17 protons and 18 neutrons. what is its mass number? what is its atomic number?

An electron is traveling with initial kinetic energy k in a uniform electric field. the electron comes to rest momentarily after traveling a distance d. (a) what is the magnitude of the electric field