(1) Although most natural potassium nuclei are stable 39 K (93.3%) or 41 K (6.7%
ID: 1486513 • Letter: #
Question
(1) Although most natural potassium nuclei are stable 39K (93.3%) or 41K (6.7%) nuclei, about 0.0117% are radioactive 40K nuclei, which have a half-life of 1.26 billion years. What fraction of all the potassium nuclei in your body will undergo radioactive decay in the next 0.62-year period?
(2)
If a nuclear reation adds an extra neutron to the nucleus of 57Fe (a stable isotope of iron), it produces 58Fe (another stable isotope of iron). Will this change in the nucleus affect the number and arrangement of the electrons in the atom that's built around this nucleus? Why or why not?
a No, the number of electrons is set by the number of protons.
b Yes, one electron will leave because of the extra neutron but the arrangement will not change.
c Yes, one electron will leave because of the extra neutron and the arrangement will change.
d No, the number of electrons is set by the number of neutrons.
(3)
Unlike heavy water, ordinary water occasionally absorbs neutrons. Why does a thermal fission reactor using an ordinary water moderator need more enriched uranium than a reactor using heavy water?
a An ordinary water moderator requires more enriched uranium so that the neutrons needed for the chain reaction are more lilkely to be absorbed by the water instead of the enriched uranium whereas a heavy water moderator absorbs all neutrons.
b An ordinary water moderator requires more enriched uranium so that the neutrons needed for the chain reaction are more lilkely to be absorbed by the enriched uranium instead of the water whereas a heavy water moderator absorbs all neutrons.
c An ordinary water moderator requires more enriched uranium so that the neutrons needed for the chain reaction are more lilkely to be absorbed by the enriched uranium instead of the water whereas a heavy water moderator doesn't absorb any neutrons.
d An ordinary water moderator requires more enriched uranium so that the neutrons needed for the chain reaction are more lilkely to be absorbed by the water instead of the enriched uranium whereas a heavy water moderator doesn't absorb any neutrons.
a No, the number of electrons is set by the number of protons.
Explanation / Answer
2) a) No, the number of electrons is set by the number of protons.
in an atom , number of electrons are only affected by the number of protons.
3 b An ordinary water moderator requires more enriched uranium so that the neutrons needed for the chain reaction are more lilkely to be absorbed by the enriched uranium instead of the water whereas a heavy water moderator absorbs all neutrons.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.