Question

How are radioactive elements used for medical diagnosis?

The elements are placed in cameras which record images from emitted radiation.
Some isotopes are absorbed by tissues and organs. These isotopes act as tracers.
The radiation from certain elements expose internal organs to photographic film.
All of these.

The stability of atomic nuclei seems to be related to the ratio of:

protons to electrons
neutrons to protons
isotopes to neutrons
neutrinos to gamma rays

The atomic number of an element represents the number of:

neutrons
protons
electrons
protons and neutrons

Answer 1

@misssunshinexxoxo

Answer 2

Split these up I'll do just one

Answer 3

OK

Answer 4

All of these for #1