Fill in the missing particles or nn ;0.j1i;3wlvhazhkg 9 zfs89reo6hauclei:
(a) $\text{n} + _{56}^{137}\text{Ba} \to ? + \gamma$
(b) $\text{n} + _{55}^{137}\text{Cs} \to _{56}^{137}\text{Ba} + 2?$
(c) $_{92}^{235}\text{U} + \text{n} \to _{38}^{90}\text{Sr} + ? + 3\text{n}$
(d) $? + \text{d} \to _{79}^{197}\text{Au} + \alpha$
where d stands for deuterium ($_{1}^{2}\text{H}$).

The isotope $_{15}^{32}\text{P}$ is produced by the reaction: $? + \text{n} \to _{15}^{32}\text{P} + \text{p}$. What must be the target nucleus?

When $_{11}^{22}\text{Na}$ is bombarded by deuterons ($_{1}^{2}\text{H}$), an $\alpha$ particle is emitted. What is the resulting nuclide?

Why are neutrons such good projectiles for producing nuclear react- valdf 9mlct5ow ;v66ions?

A proton strikes a $_{10}^{20}\text{Ne}$ nucleus, and an $\alpha$ particle is observed to emerge. What is the residual nucleus? Write down the reaction equation.

Are fission fragment): hwxexpdcw;7 9f6k/pp8 r vws $\beta^+$ or $\beta^-$ emitters? Explain.

  If $_{92}^{235}\text{U}$ released only 1.5 neutrons per fission on the average, would a chain reaction be possible?  ----待选择----yesno 
If so, what would be different?

$_{94}^{238}\text{Pu}$ releases an average of 2.5 neutrons per fission compared to 2.9 for $_{94}^{239}\text{Pu}$. Pure samples of which of these two nuclei do you think would have the smaller critical mass? Explain.

The energy from nuclear fissah wmr19 bac .5l 8-cnk6xitw/ion appears in the form of thermal energy - but the thermal energy of wha .-rta k/wx19a5mcn 8bwli ch6t?

The energy from nuclear fission appebn0d i 4gkh6.oars in the form of thermal energy - but the therma4k06bh ndog. il energy of what?

Why can't uranium be enriched by chemical 3(xow n/jnk f*means?

How can a neutron, with practically no kinetic energy, excite a pu1tz minbkobc8 +n-6wz ,/0nnucleus to the extent1o-zbb8t6 m nnz /cku,0w +npi shown in (Fig. Below)?

Why would a porous block of uranium be more likely to explode if kept un+0 av lcxw4s-bder water rather than 0w-4s vxacbl+ in air?

A reactor that uses highly esp x-qsh8b-3f nriched uranium can use ordinary water (instead of heavy water) as a moderator and still have a self-sustaining chain reaction. E-fb 3-spsx8qhxplain.

Why must the fission process release neutrons if it is to be usefulanpg +w*/m5 l ooguj/;?

Discuss the relative merits and disadvantages, including ;lg4diw5++ :vceo3 w*tjsp,s 8s ad cjpollution and safety, of power generation by fossil fuels, nuclear fissw+v83c5ds;ioa4 csw+l :tjjeps* g d,ion, and nuclear fusion.

What is the reason for thepm z kg,o gz1h9ta01o5sk3h3p "secondary system" in a nuclear reactor, (Fig. Below)? That is, why is the water heated by the fue ahkkzp zg1p31 5hg, 09mtos3ol in a nuclear reactor not used directly to drive the turbines?

Why are neutrons releasednc.)xvvv;v -w in a fission reaction?

Why do gamma particles penetrate matter more easily thaqadhede3 2;ii(/6vj-t: shi qsz4+d jn beta particles do?

A higher temperature is required for deuterium-deuterium ignition than for deutri,zrf; c8(ya/ -g-8lgx wgmjerium-tritiu/g-8i grmrlx 8ag(c jz-;fw y,m. Explain.

Light energy emitted by the Sun andqgk 4zn9zi .h,q ;/cz-wxme w: stars comes from the fusion process. What conditions in the intic:kgw h 9x .zz, wm4;zneq-q/erior of stars make this possible?

How do stars, and our Sun, maintain confinement/k.iby u0e/uo /j4 g)/r r:rxrs*jlm*lr *uak of the plasma for fusion?

What is the basic difference between fission and fu pkbj. 649;i*zfwm yupsion?

People who work aroundlcja70jte: 5v metals that emit alpha particles are trained that there is little danger from proximity or t 5e7jlcj: 0vaeven touching the material, but that they must take extreme precautions against ingesting it. Hence, there are strong rules against eating and drinking while working, and against machining the metal. Why?

Why is the recommended maximum radiation dose higher fz h8 7ifmon) a05re;gior women beyond the child-bearin);h8mi g5an zf0ior7e g age than for younger women?

Radiation is sometimes d513t w3tvxo/tj, mzzused to sterilize medical supplies and even food. Explain how it wo3todtzv/x1 5w mzt ,j3rks.

What is the difference between abp7ab/sfx:l:1ygs5 i d ihm9j1 sorbed dose and effective dose? What are the SI unit7dgjh:b1s:/xlii mf 1pa9sy5s for each?

How might radioactive tracers be used to finds wu/4 upch*j. a leak in a pipe?

Natural aluminum is 16tzc- m9, hm-qheundall $_{13}^{27}\text{Al}$. If it absorbs a neutron, what does it become? Does it decay by $\beta^-$ or $\beta^+$? What will be the product nucleus?

Determine whether the e*o ,rz5tok(8x/ )k +u81jm r ssst e.qhqxt3sreaction $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ requires a threshold energy.

Is the reaction $\text{n} + _{92}^{238}\text{U} \to _{92}^{239}\text{U} + \gamma$ possible with slow neutrons? Explain.

  Does the reaction $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ require energy, or does it release energy? How much energy?    MeV

  Calculate the energy released (or energy input reta k6dvqm .4c*quired) for the reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reaction dl8 gbenvxk(y8 ;s;- d$_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ occur if the bombarding particles have 10.00 MeV of kinetic energy? (d stands for deuterium, $_{1}^{2}\text{H}$)
(b) If so, how much energy is released?    MeV

  (a) Can the reactionqm. :f) hd s.o rbsz(i,m1tyb0 $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ occur if the incident proton has kinetic energy = 2500 keV?
(b) If so, what is the total kinetic energy of the products?    MeV

  In the reaction $_{8}^{18}\text{O} + \text{p} \to _{9}^{18}\text{F} + \gamma$, the incident $\alpha$ particles have 7.68 MeV of kinetic energy.
(a) Can this reaction occur?
(b) If so, what is the total kinetic energy of the products? The mass of $_{9}^{18}\text{F}$ is 16.999131 u.   MeV

  Calculate the Q-value for the "capture" reacrxpsnvp,khn56d ai9.9j 7m:i tion $_{2}^{4}\text{He} + _{4}^{9}\text{Be} \to _{6}^{12}\text{C} + \text{n}$.Q =    MeV

  Calculate the total kinetic energy of the products of t(n 1d t83yvveh/+u(zpa-hmp mhe reaction $_{6}^{12}\text{C} + \text{d} \to _{7}^{13}\text{N} + \text{p}$ if the incoming deuteron (d) has $KE = 36.3\ \text{MeV}$.$KE_{\text{total}}$ =    MeV

  Radioactive $_{6}^{14}\text{C}$ is produced in the atmosphere when a neutron is absorbed by $_{7}^{14}\text{N}$. Write the reaction and find its Q-value. Q =    MeV

  An example of a "stripping"gw dwm lt8a1+snc+.1a nuclear reaction is $\text{d} + _{3}^{7}\text{Li} \to \text{X} + \text{p}$.
(a) What is X, the resulting nucleus?
(b) Why is it called a "stripping" reaction?
(c) What is the Q-value of this reaction? Is the reaction endothermic or exothermic? Q =    MeV

  An example of a "pick-up" nuclear reaction t lprbjo*eg,xnj83) /is $_{1}^{2}\text{H} + _{6}^{12}\text{C} \to \text{X} + \alpha$.
(a) Why is it called a "pickup" reaction?
(b) What is the resulting nucleus?
(c) What is the Q-value of this reaction? Is the reaction endothermic or exothermic?Q =    MeV

  (a) Complete the following nuclearmcy.m w*v7-fp 1xqp8k reaction: $\text{p} + ? \to _{16}^{32}\text{S} + \gamma$.
(b) What is the Q-value? Q =    MeV

  The reaction $_{9}^{19}\text{F} + \text{n} \to _{9}^{20}\text{F} + \gamma$ requires an input of energy equal to 2.453 MeV. What is the mass of $_{9}^{20}\text{F}$?$m_{^{18}_{9}F}$ =    U

  Calculate the energy released in the f q ws..cm+sn-bission reaction $_{92}^{235}\text{U} + \text{n} \to _{56}^{141}\text{Ba} + _{36}^{92}\text{Kr} + 3\text{n}$. Use Appendix B, and assume the initial kinetic energy of the neutron is very small. Q =    MeV

  What is the energy released in the fission rean14k hj glo)ep*j/a6bu) eb z*aew3;u ction of Eq. 31-4? (The masses of j h)e bagwku3nu41lpe6z/o) *e ab; *j$_{56}^{140}\text{Ba}$ and $_{36}^{92}\text{Kr}$ are 140.914411 u and 91.926156 u, respectively.) Q =    MeV

  How many fissions takeeux*uvl1ts2 (ncy0s jy8f s,+ place per second in a 200-MW reactor? Assume 200 MeV is released per fissio0y1e82us+yn*v sc lf, txus(j n. P =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a fission reactor is about 200 MeV per fission. What fra oc/ 4nf7u n7elje6o5yction of the rest e/ynfo 7 joc46elu57nmass of a $_{92}^{235}\text{U}$ nucleus is this?$\approx1/$   

  Consider the fission reacl+jic8 mzoa9/-5c3me je : kz5sfsrh.tion $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(a) How many neutrons are produced in this reaction?   
(b) Calculate the energy release. The atomic masses for Sb and Nb isotopes are 132.915250 u and 97.910328 u, respectively. Q =    MeV

  How much mass of $_{92}^{235}\text{U}$ is required to produce the same amount of energy as burning 1.0 kg of coal (about $3 \times 10^7\ \text{J}$)?    $ \times 10^{-7}\ \text{kg}$

  Suppose that the electric-7y(r ig-7ecake.1hg var qb ) average power consumption, day and night, in a typical house is 950 W. What i7 cia7 r-v.rg)(yhbg kq e-a1enitial mass of $_{92}^{235}\text{U}$ would have to undergo fission to supply the electrical needs of such a house for a year? (Assume 200 MeV is released per fission, as well as 100% efficiency.)    $ \times 10^{-4}\ \text{kg}$

  What initial mass of;f x t7wz *pxct63lwd8ihty+6 $_{92}^{235}\text{U}$ is required to operate a 650-MW reactor for 1 yr? Assume 40% efficiency.$\approx $    $\ \text{kg U}$

  Assuming a fission of rwas11, kycp;c4iin iiu uz5 /7xi*g; $_{92}^{235}\text{U}$ into two roughly equal fragments, estimate the electric potential energy just as the fragments separate from each other. Assume that the fragments are spherical (see Eq. 30-1) and compare your calculation to the nuclear fission energy released, about 200 MeV.
PE =    MeV
This is about    % larger than the nuclear fission energy released.

  What is the average kinetic energy ltetc)d(alhj4d y4.efl; r2 -of protons at the center of a star where the temperarltt(deh dlj; 24cy-f) le4.ature is $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

Show that the energy released in the fusion reactionhx)1 vw7+h oo0p;hit w $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is 17.59 MeV.

Show that the energy released when two+:fvmh557 v8rzuj hbt bj t88w deuterium nuclei fuse to form $_{2}^{3}\text{He}$ with the release of a neutron is 3.27 MeV.

  Verify the Q-value stated for each of the reactions ofEqs. 6. [Hint: Be careful with electrons.]

6-b Q =    MeV
6-C Q =    MeV

  Calculate the energy release per gram of fuel for the reactions of Eqs. 8a, b+d*icd5j,m;f 7ete8hxs j(lf , and c. Compare to the e xht;i(57sjcdjm8 e + *,ffdelnergy release per gram of uranium in fission.
8a =    $ \times 10^{23}\ \text{MeV/g}$
8b =    $\times 10^{23}\ \text{MeV/g}$
8c =    $ \times 10^{24}\ \text{MeV/g}$
Uranium fission =    $ \times 10^{23}\ \text{MeV/g}$

  How much energy is r sao8/;lym+ gwzsb+k5 eleased when $_{92}^{238}\text{U}$ absorbs a slow neutron ($KE \approx 0$) and becomes $_{92}^{239}\text{U}$? Q =    MeV

  If a typical house requires 950 W of electric power on av m.t9 ud7t ngjgq746zlerage, what minimum amount of deuterium fuel would have to be use7tg n49gl.jm6 d7uztq d in a year to supply these electrical needs? Assume the reaction of Eq. 8b.    g

Show that the energiesti6o8na/ hsc( carried off by the $_{2}^{4}\text{He}$ nucleus and the neutron for the reaction of Eq. 8c are about 3.5 MeV and 14 MeV, respectively. Are these fixed values, independent of the plasma temperature?

  Suppose a fusion reactor ran on "d-d" reac-xd2v*1(g xv m 51cj xygcbj)fo1 zdjo+ f)m(ntions, Eqs. 8a and b. Estimate how much water, for fuel, would be needed per hour to run axno-dvj5)g gyf dz* 1o2v)mxjx+1 m((cc1jb f 1000-MW reactor, assuming 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is contained in 1.00 .k9rrg m/5 e 2eymfab8kg of water if its natural deuterium is used in the fusion reaction of Eq. 318k9re rbmfe2yagm ./ 5-8a? Compare to the energy obtained from the burning of 1.0 kg of gasoline, about $5 \times 10^7\ \text{J}$.
   $ \times 10^{9}\ \text{J}$
   times more than gasoline

The energy output of massive stars is believetfdil p7,:a6 gu7z2 xgd to be due to the carbon cycle (see text). (a) Sh 2:iu6tlagg7fxzp7 d ,ow that no carbon is consumed in this cycle and that the net effect is the same as for the proton-proton cycle. (b) What is the total energy release? (c) Determine the energy output for each reaction and decay. (d) Why does the carbon cycle require a higher temperature ($T \approx 2 \times 10^7\ \text{K}$) than the proton-proton cycle ($T \approx 1.5 \times 10^7\ \text{K}$)?

(a) Compare the energy needed for the first reaction of the cxq b e67i*-vx(aeg f0 p0(jigfarbon cycle to that for a deuterx ieae(gb6(f7j00fqgp*i vx- ium-tritium reaction.
(b) If a deuterium–tritium reaction requires $T \approx 3 \times 10^8\ \text{K}$, estimate the temperature needed for the first carbon-cycle reaction.

  A dose of 4.0 Sv of m0 dt90ctcov 4$\gamma$ rays in a short period would be lethal to about half the people subjected to it. How many grays is this?    $Gy$

  Fifty rads of $\alpha$-particle radiation is equivalent to how many rads of X-rays in terms of biological damage?    rad

  How many rads of slow neutrons will do as much biologica,s /2f8+v ecopxmey5u fu3)r;4etmv8 l( osrm l damage as 75 rads of fafeye 4v+u; tmmoom)r l 2x ps(s8r/ ,uf3c5ev8st neutrons?    rad slow neutrons

  How much energy is deposited in the bodyb9 suaksi 41/ d;mxej- z0we3e of a 65-kg adult exposed to a 2.0-Gy dowses31x-4zd0 ejume iab/ 9k;se?    $J$

  A $0.025-\mu\text{Ci}$ sample of $_{15}^{32}\text{P}$ is injected into an animal for tracer studies. If a Geiger counter intercepts 25% of the emitted $\beta^-$ particles, what will be the counting rate, assumed 85% efficient?$\approx$    $ \ \text{counts/s}$

  A cancer patient is undergoing radwd3 y,*(q/;7 kt:xtuqidqdy iiation therapy in which protons with an energy of 1.2 MeV are incident on a y/,t;kd7txqiy( *3ui w qdd:q0.25-kg tumor.
(a) If the patient receives an effective dose of 1.0 rem, what is the absorbed dose?
(b) How many protons are absorbed by the tumor? Assume $QF = 1$.    $ \times 10^{10}\ \text{p}$

  A 1.0-mCi source of j* ; 3s1jd,i zrbtam ku967qsk$_{15}^{32}\text{P}$ (in $\text{NaHPO}_4$), a $\beta^-$ emitter, is implanted in a tumor where it is to administer 36 Gy. The half-life of $_{15}^{32}\text{P}$ is 14.3 days, and 1 mCi delivers about $10\ \text{mGy/min}$. Approximately how long should the source remain implanted?    day

About 35 eV is required to produce one ion pair in a( 6vn j -hhof,g7x/saeir. Show that this is consistent with the two definiti h7 (,eafvgnx-js/6ho ons of the roentgen given in the text.

  $_{27}^{57}\text{Co}$ emits 122-keV $\gamma$ rays. If a 70-kg person swallowed $1.85\ \mu\text{Ci}$ of $_{27}^{57}\text{Co}$, what would be the dose rate (Gy/day) averaged over the whole body? Assume that 50% of the $\gamma$ energy is deposited in the body.    $\times 10^{-2}\ \text{Gy/day}$

  What is the mass of az se by1edc89;x6/afw $1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioactivvlx(g) 9jhu k9a7xz/c e $_{53}^{131}\text{I}$ were released in the accident at Chernobyl in 1986. Chemically, iodine goes to the human thyroid. (Doctors can use it for diagnosis and treatment of thyroid problems.) In a normal thyroid, $_{53}^{131}\text{I}$ absorption can cause damage to the thyroid.
(a) Write down the reactions for the decay of $_{53}^{131}\text{I}$.
(b) Its half-life is 8.0 d; how long would it take for ingested $_{53}^{131}\text{I}$ to become 10% of the initial value? N $\approx$    $ \ \text{d}$
(c) Absorbing 1 mCi of $_{53}^{131}\text{I}$ can be harmful; what mass of iodine is this?   $ \times 10^{-12}\ \text{kg}$

  Assume a liter of milk typicayw 4ww x51ffcmmpst.9 (b7 uc7lly has an activity of 2000 pCi due to $_{19}^{40}\text{K}$. If a person drinks two glasses (0.5 L) per day, estimate the total effective dose (in Sv and in rem) received in a year. As a crude model, assume the milk stays in the stomach 12 hr and is then released. Assume also that very roughly 10% of the 1.5 MeV released per decay is absorbed by the body. Compare your result to the normal allowed dose of 100 mrem per year. Make your estimate for
(a) a 50-kg adult, $\approx$    $ \times 10^{-7}\ \text{Sv/year}$ $\approx $    $ \times 10^{-5}\ \text{rem/year}$ $\approx $    $ \times 10^{-4}$ times the allowed dose
(b) a 5-kg baby.   $\times 10^{-4}\ \text{Sv}$    $\times 10^{-4}\ \text{rem}$    $ \times 10^{-4}\ \text{times the allowed dose}$

Radon gas, $_{86}^{222}\text{Rn}$, is considered a serious health hazard (see discussion in text). It decays by $\alpha$ emission.
(a) What is the daughter nucleus?
(b) Is the daughter nucleus stable or radioactive? If the latter, how does it decay, and what is its half-life?
(c) Is the daughter nucleus also a noble gas, or is it chemically reacting?
(d) Suppose 1.0 ng of $_{86}^{222}\text{Rn}$ seeps into a basement. What will be its activity? If the basement is then sealed, what will be the activity 1 month later?

  Calculate the wavelength of photons zdm :x.z-6tw(e;) ncabxp (jpneeded to produce NMR transitions in free protons in a 1.000-Tajm( .d:6xn xpbe( pz;cw t-)z field. In what region of the spectrum does it lie? c =    $m$

  J. Chadwick discovered the neutron /4bzm p(2rqytby bombarding $_{4}^{9}\text{Be}$ with the popular projectile of the day, alpha particles.
(a) If one of the reaction products was the then unknown neutron, what was the other product?
(b) What is the Q-value of this reaction?Q =    MeV

  Fusion temperatures are often given in keV. Determine the conversio3hi;od jbj/a;-vy1nk n factor from kelvins to keV using, as is common vhaj 3 dby1;i/k jn;o-in this field, $KE = kT$ without the factor $\frac{3}{2}$. K =    $ \times 10^{-5}\ \text{keV/K}$

  One means of enriching uranius,/xoouq k *i0(fw/ddm is by diffusion of the gas $\text{UF}_6$. Calculate the ratio of the speeds of molecules of this gas containing $_{92}^{235}\text{U}$ and $_{92}^{238}\text{U}$ on which this process depends.    :1

  (a) What mass of $_{92}^{235}\text{U}$ was actually fissioned in the first atomic bomb, whose energy was the equivalent of about 20 kilotons of TNT (1 kiloton of TNT releases $5 \times 10^{12}\ \text{J}$)? $\approx $    $\ \text{kg}$
(b) What was the actual mass transformed to energy?$\approx $    $\ \text{g}$

  In a certain town the average yearly background radiation consists of 21 mradjk +3ymn :j:cs of X-rays ann: kj3jc:my+ sd $\gamma$ rays plus 3.0 mrad of particles having a QF of 10. How many rem will a person receive per year on the average?dose(rem) =   $ \times 10^{-2}\ \text{rem/yr}$

  Deuterium makes up 0.011rximee+dmz j1 .2hc ;05% of natural hydrogen on average. Make a rough estimate of the total deuterium in the Earth's oceans and estimate the total energy released if xmjh;c2e e i d.1r0+mzall of it were used in fusion reactors.
$\approx $    $ \times 10^{15}\ \text{d atoms}$
$\approx$    $ \times 10^{16}\ \text{kg d}$
   $\times 10^{30}\ \text{J}$

  A shielded $\gamma$-ray source yields a dose rate of $0.052\ \text{rad/h}$ at a distance of 1.0 m for an average-sized person. If workers are allowed a maximum dose of 5.0 rem in 1 year, how close to the source may they operate, assuming a 40-h work week? Assume that the intensity of radiation falls off as the square of the distance. (It actually falls off more rapidly than $\frac{1}{r^2}$ because of absorption in the air, so your answer will give a better-than-permissible value.)    m

Radon gas, $_{86}^{222}\text{Rn}$, is formed by $\alpha$ decay. (a) Write the decay equation. (b) Ignoring the kinetic energy of the daughter nucleus (it's so massive), estimate the kinetic energy of the $\alpha$ particle produced. (c) Estimate the momentum of the alpha and of the daughter nucleus. (d) Estimate the kinetic energy of the daughter, and show that your approximation in (b) was valid.

  Consider a system of nucleam7)m v41lrqfq r power plants that produce 3400 MW.
(a) What total mass of $_{92}^{235}\text{U}$ fuel would be required to operate these plants for 1 yr, assuming that 200 MeV is released per fission? $\approx$    $ \ \text{kg}$
(b) Typically 6% of the $_{92}^{235}\text{U}$ nuclei that fission produce $_{38}^{90}\text{Sr}$, a $\beta^-$ emitter with a half-life of 29 yr. What is the total radioactivity of the $_{38}^{90}\text{Sr}$ in curies, produced in 1 yr? (Neglect the fact that some of it decays during the 1-yr period.) $\dfrac{\Delta N}{\Delta t}$    $ \times 10^{6}\ \text{Ci}$

  In the net reaction,, for the proton-proton3gq5o1t/x u hn cycle in the Sun, the neutrinos escape from the Sun with energy of about 0.5 MeV. The remaining energy, 26.2 MeV, is available w3xn51 /hquot githin the Sun. Use this value to calculate the "heat of combustion" per kilogram of hydrogen fuel and compare it to the heat of combustion of coal, about $3 \times 10^7\ \text{J/kg}$.    $ \times 10^{-14}\ \text{J/g}$
This is about    $ \times 10^7$times the heat of combustion of coal.

  Energy reaches Earth from nw dhww+.o:zk8;cc:wthe Sun at a rate of about $1400\ \text{W/m}^2$. Calculate
(a) the total power output of the Sun,$\approx $    $ \times 10^{26}\ \text{W}$
(b) the number of protons consumed per second in the reaction of Eq. 7, assuming that this is the source of all the Sun's energy. $\approx $    $ \times 10^8\ \text{protons/s}$
(c) Assuming that the Sun's mass of $2 \times 10^{30}\ \text{kg}$ was originally all protons and that all could be involved in nuclear reactions in the Sun's core, how long would you expect the Sun to "glow" at its present rate? See previous Problem.$ \approx $    $ \times 10^{11}\ \text{yr}$

  Some stars, in a later stage of evolution, may begin to fuvr *1m/u0nhlrp1 djtj a r2)v5se two $_{6}^{12}\text{C}$ nuclei into one $_{12}^{24}\text{Mg}$ nucleus.
(a) How much energy would be released in such a reaction?
(b) What kinetic energy must two carbon nuclei each have when far apart, if they can then approach each other to within 6.0 fm, center-to-center? KE =    $ \times 10^{-13}$ =    MeV
(c) Approximately what temperature would this require?   $ \times 10^{10}\ \text{K}$

  An average adult body contains about r3wg x1bdcbb;6- j dier::2wj$0.10\ \mu\text{Ci}$ of $_{19}^{40}\text{K}$, which comes from food.
(a) How many decays occur per second?    $\ \text{decays/s}$
(b) The potassium decays produce beta particles with energies of around 1.4 MeV. Calculate the dose per year in sieverts for a 50-kg adult.    $\times 10^{-4}\ \text{Sv/y}$
Is this a significant fraction of the $3.6\ \text{mSv/year}$ background rate?    %

  When the nuclear reac 6igb7r etp5h(hr/a7 wtor accident occurred at Chernobyl in 1986, $2.0 \times 10^7\ \text{Ci}$ were released into the atmosphere. Assuming that this radiation was distributed uniformly over the surface of the Earth, what was the activity per square meter? (The actual activity was not uniform; even within Europe wet areas received more radioactivity from rainfall). $\frac{\text{Activity}}{\text{m}^2}$=   $ \times 10^{3}\ \text{decays/s}$

  A star with a large helium abundance can burn heliumsw6: qd0v1 fu (hlqng3 in the reaction $3\ _{2}^{4}\text{He} \to _{6}^{12}\text{C} + \gamma$. What is the Q-value for this reaction? Q =    MeV

  A $1.0-\mu\text{Ci}\ _{55}^{137}\text{Cs}$ source is used for 2.0 hours by a 75-kg student in a physics lab. Radioactive $_{55}^{137}\text{Cs}$ decays by $\beta^-$ decay with a half-life of 30 years. The average energy of the emitted betas is about 190 keV per decay. The $\beta^-$ decay is quickly followed by a $\gamma$ ray with an energy of 660 keV. Assuming the student absorbs all emitted energy, what effective dose (in rem) is received during lab? dose $\approx $    $ \times 10^{-5}\ \text{rem}$

  A large amount of $_{38}^{90}\text{Sr}$ was released during the Chernobyl nuclear reactor accident in 1986. The $_{38}^{90}\text{Sr}$ enters the body through the food chain. How long will it take for 90% of the $_{38}^{90}\text{Sr}$ released during the accident to decay? See Appendix B.$\approx $    y

Three radioactive sources have the same activity, 25 mCi. So7xx lnr4z e*v:urce A emits 1.0-MeV lr v7*4ex xnz:$\gamma$ rays, source B emits 2.0-MeV $\gamma$ rays, and source C emits 2.0-MeV alphas. What is the relative danger of these sources?

  A 70-kg patient is to be given a medical test involving the ingestion z82y yr*x8d69yrq a i wu4yi5v7oe(xeof $_{43}^{99\text{m}}\text{Tc}$ (Section 31-7) which decays by emitting a 140-keV gamma. The half-life for this decay is 6 hours. Assuming that about half the gamma photons exit the body without interacting with anything, what must be the initial activity of the Tc sample if the whole-body dose cannot exceed 50 mrem? Make the rough approximation that biological elimination of Tc can be ignored. Activity $\simeq $    $\ \text{mCi}$