Which would result in radioactive decay? check all that apply.

a)a neutron-to-proton ratio of 1: 1 in a small nucleus

b)a neutron-to-proton ratio of 1: 2 in a large nucleus

c)a nucleus that contains 90 protons and 100 neutrons

d)a nucleus that contains 8 protons and 8 neutrons

e)any isotope of the element uranium, which has atomic number 92

f)any isotope of the element potassium, which has atomic number 19