Fill in the missing particles or nucle2ouo5 sp o7c4fi:
(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 rec+jrd umgm(-u6 d1g 3uactions?

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 fragments 9k8 *xckn wfom1+rhntz*zr9/$\beta^+$ 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 nucleac m:(+h,k )e.7 igu aluqbcc3dr fission appears in the form of thermal energy - but the thermcb ghcalm.+7,dk :ceui3q(u) al energy of what?

The energy from nuclear f 9c/ ehcigkx6m k 0w.)h.ji3vb- qyg/sission appears in the form of thermal energy - but the thermal energy of what ib0ch9 iq 6s /m-kgc3vyxwj.g)h./ke?

Why can't uranium be enriched by chemical mn3a0 4l)lz ves*wi)uweans?

How can a neutron, with practically no kinetic energy, excite a nucleus to the e9,8,spfz-zeg) bmcf* 07 vx lu2utlovxtent shown in 0m,8* uffvux,s g tl7pz o el9vbcz2)-(Fig. Below)?

Why would a porous block of uranium be more likely to explode if kept under watane5u. knl0af3 /8wgyer rather than ig3afkuey wa5.n /0n8 ln air?

A reactor that uses highly enriched uranium can7zoabv4e .0;wfo p od+ use ordinary water (instead of heavy water) as a moderator and still have a self-sustaining chain reacti vf z47;odo.e powa+b0on. Explain.

Why must the fission.d9/zcudca r: process release neutrons if it is to be useful?

Discuss the relative m xd5s;,z.u q8p,y(f:umvbd qf0 i gz)perits and disadvantages, including pollution and safety, of power generation by fossil fuels, nuclear fission, zf( sfp,mg.i,qb:;uxdzy0d qv 8 up5) and nuclear fusion.

What is the reason for0 ne8o 9py/yfjynjq6 e w:mwxney:;2. the "secondary system" in a nuclear reactor, (Fig. Below)ny8m/nyeeqxn6 w jy0 joy w. 9p::ef;2? That is, why is the water heated by the fuel in a nuclear reactor not used directly to drive the turbines?

Why are neutrons released in a fa0l2b 7eaw ka/ission reaction?

Why do gamma particles penetratcz4*el gvmp;,b9/ p4dl pd)cxe matter more easily than beta particles do?

A higher temperature is required for deuterium,loo y .z.u;4fxjawr3 -deuterium ignition than for deuterium-tritium. Explain.flj xu3zry;,o aw 4.o.

Light energy emitted by 5 us kuwgir0(,the Sun and stars comes from the fusion process. What conditions in the interior of stars make thisi0w 5us ,krg(u possible?

How do stars, and our Sun, maintain confinement of the plagmqstl52/dd /4fyz- l sma for fusion?

What is the basic differencew9+vmag+ r*r:nzwc ,i between fission and fusion?

People who work around metals that emit alpha particles are trained thatqix gl5(h. 3vw:zou2i there is little danger from proximity or even touching the material, but that they must take extreme precautions against ingesting it. Hence, thv2i(z3.q:5wg oxihul ere are strong rules against eating and drinking while working, and against machining the metal. Why?

Why is the recommended maximum g mg.*cxhpo; 7radiation dose higher for women beyond the child-bearing age than for young.o m;c7 gpxh*ger women?

Radiation is sometimes usedv*a6 7ap701)mrt:npu fop xyi5rm5be to sterilize medical supplies and even food. Explain how it work:y rome7p*)fppmnr a7i 6 ba5u5t0xv1s.

What is the difference ;6y e tyh nlc,6k,jp eil8t2h(between absorbed dose and effective dose? What are the SI units fnehye,t,8 (py2hcl kj t 66li;or each?

How might radioactive tracers be used to find ahn wc73*y c8vp leak in a pipe?

Natural aluminum is almc 6 +n4,bvfwgl $_{13}^{27}\text{Al}$. 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 rbx vzc*+jt8u5eaction $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ 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 requirtr 9kej 6*2rgf- 8vdg+0mv zjled) for the reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reaction 95b h2u0 ra, 6 7d srgozxie;hqtbpl5uf f/:b*$_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ 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 reaction r8 g t.px,*ey g-mvj9;coo8mv$_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ 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" reactio1q9 i cocuof+;cb5+z4fuf,wi n $_{2}^{4}\text{He} + _{4}^{9}\text{Be} \to _{6}^{12}\text{C} + \text{n}$. Q =    MeV

  Calculate the total kinetic enez89en ,b0zwi drgy of the products of the 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" nuclear reac mz3..zzd 6 x0tw5ehqiz8+1jv at98kegwul 4htion 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 i pku9shm9y*,tc,tx6 js $_{1}^{2}\text{H} + _{6}^{12}\text{C} \to \text{X} + \alpha$.
(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 nuclear reahmow.,nd 2o q8ction: $\text{p} + ? \to _{16}^{32}\text{S} + \gamma$.
(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 tqeflx8 2 lh3,bhe fission 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 reaction of Eqtkpm)r ue4 1i-. 31-4? (The masses of rkipt)mue1 -4$_{56}^{140}\text{Ba}$ and $_{36}^{92}\text{Kr}$ are 140.914411 u and 91.926156 u, respectively.) Q =    MeV

  How many fissions take place per second in a 200-MW reactor? Assume 200-mk5 *je92em5 c 9yl3dv*dns p y/mvmx MeV is released l3ymm j *n52 dkx5v- 9vee9*cd/mmpysper fission. P =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced bylpol.p0 s 9b7i a fission reactor is about 200 MeV per fission. What fracti 0oll p97ips.bon of the rest mass of a $_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fission reaction yzkao( f cltp820eb;bh+m2*iyuv/ e rh.n:-y$_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(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 average power consumptiq z7uqrh 2+p+zon, day and night, in a typical house is 950 W. What initial q z+qh27 rz+upmass 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 ofy,o7d8/ cocyl $_{92}^{235}\text{U}$ is required to operate a 650-MW reactor for 1 yr? Assume 40% efficiency. The initial mass is $\approx $    $\ \text{kg}$

  Assuming a fission ofha3/ 5 ,juhaum $_{92}^{235}\text{U}$ 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 of iz n vg+0z:+9osifd lw- xfm6,protons at the center of a star where the tempera+n6s vz-m9gf:zd0 iw lf+x,i oture is $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy released in the fus6viyf4n4jm2uaf/wn ;b5j h7 gion reaction $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is    MeV.

  Calculate the energy rebuk./vtqv3vb+;/ fqeleased when two deuterium nuclei fuse to form $_{2}^{3}\text{He}$ with the release of a neutron is    MeV.

  Verify the Q-value statear 2/ekoinzz1u) t+ ,cd for each of the reactions ofEqs. 31-6.
Eqs. 31-6-a Q =    MeV
Eqs. 31-6-b Q =    MeV
Eqs. 31-6-c Q =    MeV

  Calculate the energy release pet b/jcxav;i7h; - osge06n)ggfvk k a1/ dv9+er gram of fuel for the reactions of Eqs. 31-8a, b, and c. Compare to the energy release per gram of uranium b a-e79knxs/cgkggo)jvdf/ea; t1 ;i+6h v0 v in fission.
31-8a =    $ \times 10^{23}\ \text{MeV/g}$
31-8b =    $\times 10^{23}\ \text{MeV/g}$
31-8c =    $ \times 10^{24}\ \text{MeV/g}$
Uranium fission =    $ \times 10^{23}\ \text{MeV/g}$

  How much energy is released whi f29 c-gwkgx7en $_{92}^{238}\text{U}$ 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 average, what minim -qalcbx0+ r7rum amount of deuterium fuel would have to blq7 -ac rxb0+re used in a year to supply these electrical needs? Assume the reaction of Eq.31- 8b.    g

Show that the energies carried off bms))j n82;5p vsj+mhw utbm(uc8t/ffy the $_{2}^{4}\text{He}$ nucleus and the neutron for the reaction of Eq. 31-8c 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" reactions, Eqs. 31-8a and b.no*m/f(-oz f a5+ eaz(4 ucjso Estimate how muchaf e*-m c4s+j uo/of5z(o naz( water, for fuel, would be needed per hour to run a 1000-MW reactor, assuming 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is contained in 1.00 kg of water bqy-c+i m8d.x if its natural deuterium is used in theibc x -8dmq+.y fusion reaction of Eq. 31-8a? 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 believed to be d3uhu;z/ez ( gzue to the carbon cycle (see text). (a) Show 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 ener3(ze/uzuzg ; hgy 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* dbdr63s) qr-h9zbs rg0fwd)a2 u1ue carbon cycle to that for a deuterium-tritium reactsb3r*1 ga2bwrdzeud0 ))d q96fu-hrsion.
(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 ue38.:td hs;dvu c,af $\gamma$ 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 d3-k piu-g q0 xhd.45gf en5mhso as much biological damage as 75 rads of fast neutronmk g-34 en xud5p5sh-hi0q fg.s?    rad slow neutrons

  How much energy is depositk+c 7* 7rp- f7desqooked in the body of a 65-kg adult exposed to a 2.0-Gy dosokqsr 7+ kd7-7foc* epe?    $J$

  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 r*p2n4uzf s-qundergoing radiation therapy in which protons with an energy of 1rfpsn-2* qzu4.2 MeV are incident on a 0.25-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 .0y.rrljd kci/8fes/ $_{15}^{32}\text{P}$ (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 trb ud1fsl s6,5x;g1 jwo produce one ion pair in air. Show that this is consistent with the u1rxsj wsb6g, ;l5f d1two definitions 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 jh6ov2p:i j233oj ih fa $1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioacti0o+ zgzbx pi-k1nbf96ve $_{53}^{131}\text{I}$ 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 fmtb8 j3 yu5(:bivf ;mtypically 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 needed to produce NMR transim-khs. jvl egs3*qg75tions in free protons in a 1.000-T field. In what region of tv-s7e. m*jg5k g qslh3he spectrum does it lie? c =    $m$

  J. Chadwick discovered the neutron by bombaj)uc t(as giqpk;e3);u 7v9ji rding $_{4}^{9}\text{Be}$ 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 t3zy u 9:qps*inhe conversion factor from kelvins to keV using, as is comupzns9 3 :yqi*mon in this field, $KE = kT$ without the factor $\frac{3}{2}$. K =    $ \times 10^{-5}\ \text{keV/K}$

  One means of enriching uraniusk7,thj;szd : m 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 mws*5b wpgh v v//1u0 vzs6a7pprad of X-rays a p/bwap5sv vvsu 7 1*0gph6z/wnd $\gamma$ 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 0.0115% of natural hp u0:0ezs3uqdt5fz-c6z yl +d ydrogen on average. Make a rough estimate of the total deuterium in d zu6e0 0ls 5-:3tzq pdfyucz+the Earth's oceans and estimate the total energy released if all of it were used in fusion reactors.

The total mass of deuterium is about    $ \times 10^{16}\ \text{kg}$
The total energy is about    $\times 10^{30}\ \text{J}$

  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 nuclear power plants that produce 3400 MW.gs (:13 drm2m3rcwm d*gfpl6s
(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-proton cycle in the Sun, the neutrinos es +6:e:h3id ywavzwww3cape from the Sun with energy of about 0.5 MeV. The remaining energy, 26.2 MeV, is available within the Sun. Use this value to calculate th6a3:he+ wdv w: zywwi3e "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 the Sun at a rate of abobgv5n-f, sp7al7j9mm 6b6 h l 5/ruhokut $1400\ \text{W/m}^2$. 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.31- 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 latert : 4 kiapou- 0isv+*w-.ifkdb stage of evolution, may begin to fuse 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 5tsv4gih0: vs$0.10\ \mu\text{Ci}$ 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 reactor accident occurred at Chernobyvr or3y.7ge. ql 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 abunda1zf* kmckl (evdz+6 w:nce can burn helium 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 o.)lzzw9v7 ud ocf w8dtt(-h9same activity, 25 mCi. Source A emits 1.0-MeVud-9zht.8 9to()cdo lf7 wv zw $\gamma$ 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 ingestionu*9f1 pbe4wcdixxs;qq 4hk 49 of $_{43}^{99\text{m}}\text{Tc}$ (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 $    $\ \text{mCi}$