Predicting nuclear stability is important when determining whether or not a nuclear reaction can take place spontaneously. use the following set of guidelines to predict the nuclear stability of the elements listed below.

1. stable nuclei have a high neutron-to-proton ratio, greater than 1.25 beyond atomic number 40 and continuing to rise at higher atomic numbers.
2. the majority of stable nuclei have even numbers of neutrons and protons. odd-even and even-odd combinations can be stable but stability is less likely.
3. nuclei that have the magic numbers of 2, 8, 20, 28, 50, or 82 protons or 2, 8, 20, 28, 50, 82 or 126 neutrons are more stable than nuclei that do not contain these numbers.
4. nuclei that have atomic numbers greater than 83 are unstable. nuclei are considered stable if one or more criteria are met.

a) unstable

b) unstable

c) unstable

d) Stable

Explanation:

a)

The given isotope , atomic number is greater than 83.(84>83).

Therefore, it is unstable.

b)

The given isotope  has even number of protons(15) and neutrons(15).

Therefore, it is unstable.

c)

The given isotope  has even number of protons(15).

Therefore, it is unstable.

d)

The given isotope have even number of neutrons ( 68) an d the proton ratio is .It is more than 1.25.

Therefore, it is stable.

answer; i believe the correct answer is (c) /// is a homogeneous mixture of gaseous substance nitrogen,oxygen and smaller amounts of other substancesmixtures can be either ( homogeneous or heterogeneous)plz check first good luck

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.