Question: Find the energy released in the fusion

> One day, Leslie prepared a new snack to serve at preschool: celery stuffed with ricotta cheese and pineapple. The first time she served it, few children touched it. How can Leslie encourage the children to accept the snack? What tactics should she avoid?

> Mandy and Jeff are parents of 2-year-old inhibited Sam and 3-year-old irritable Maria. Explain the importance of effortful control to Mandy and Jeff, and suggest ways they can strengthen it in each of their children.

> When Timmy was 18 months old, his mother stood behind him, helping him throw a large ball into a box. As his skill improved, she stepped back, letting him try on his own. Using Vygotsky’s ideas, explain how Timmy’s mother is supporting his cognitive deve

> Eight-month-old Shaun is well below average in height and painfully thin. What serious dietary disease does he likely have, and what types of intervention, in addition to dietary enrichment, can help restore his development?

> Which of the capacities listed in Table 6.2 indicate that mental representation emerges earlier than Piaget concluded? Data from Table 6.2:

> Explain how either too little or too much stimulation can impair cognitive and emotional development in the early years.

> Sharon, a heavy smoker, has just arrived at the hospital in labour. Which one of the medical interventions discussed in the preceding sections is her doctor justified in using?

> Contrast the positive impact of the baby’s production of high levels of stress hormones during childbirth with the negative impact of severe maternal stress on the fetus?

> Why is it incorrect for couples who postpone childbearing until age 35 or later to conclude that medical advances can overcome fertility problems?

> Explain why parents of children with genetic disorders often experience increased stress. What factors, within and beyond the family, can help these parents support their children’s development?

> Review Reiko’s story in the introduction to this chapter. What factors likely contributed to her resilience in the face of wartime persecution, relocation, and internment?

> Should parents try to promote children’s self-esteem by telling them they’re “smart” or “wonderful”? Explain.

> Nine-year-old Adrienne spends many hours helping her father build furniture in his woodworking shop. How might this experience facilitate Adrienne’s advanced performance on Piagetian seriation problems?

> Joey complained to his mother that it wasn’t fair that his younger sister Lizzie was almost as tall as he was. He worried that he wasn’t growing fast enough. How should Rena respond to Joey’s concern?

> On a hike with his family, 5-year-old Ryan became frightened when he reached a steep section of the trail. His father gently helped him climb up while saying, “Can you be brave? Being brave is when you feel scared but you do it anyway.” What aspect of em

> Three-year-old Will understands that his tricycle isn’t alive and can’t feel or move on its own. But at the beach, while watching the sun dip below the horizon, will exclaimed, “The sun is tired. It’s going to sleep!” What explains this apparent contradi

> Dental check-ups revealed a high incidence of untreated tooth decay in a U.S. preschool program serving low-income children. Using findings presented in this and previous chapters, list possible contributing factors.

> Amy, two months pregnant, wonders how the embryo is being fed and what parts of the body have formed. “I don’t look pregnant yet, so does that mean not much development has taken place?” she asks. How would you respond to Amy?

> Why do children of depressed parents have difficulty regulating emotion? What implications do their weak self-regulatory skills have for their response to cognitive and social challenges?

> Two protons approach each other with 70.4 MeV of kinetic energy and engage in a reaction in which a proton and a positive pion emerge at rest. What third particle, obviously uncharged and therefore difficult to detect, must have been created?

> Fill in the missing particle. Assume that (a) occurs via the strong interaction while (b) and (c) involve the weak interaction. (a) (b) (c)

> Occasionally, high - energy muons collide with electrons and produce two neutrinos according to the reaction μ+ + e- ( 2v. What kind of neutrinos are they?

> Find the energy released in the fission reaction n + 23592U ( 4098Zr + 13552Te + 3n The atomic masses of the fission products are 97.9120 u for 4098Zr and 134.9087 u for 13552Te.

> Find the energy released in the fusion reaction 11H + 23He ( 24He + e+ + v

> Name at least one conservation law that prevents each of the following reactions from occurring. (a) (b) (c)

> A ∑0 particle traveling through matter strikes a proton. A ∑+, a gamma ray, as well as a third particle, emerge. Use the quark model of each to determine the identity of the third particle.

> What is the electrical charge of the baryons with the quark compositions (a) ūūd- and (b) ūd-d-? What are these baryons called?

> Identify the particles corresponding to the quark states (a) suu, (b) ūd, (c) s-d, and (d) ssd.

> The quark compositions of the K0 and Λ0 particles are ds- and uds, respectively. Show that the charge, baryon number, and strangeness of these particles equal the sums of these numbers for their quark constituents.

> In the theory of quantum chromodynamics, quarks come in three colors. How would you justify the statement, “All baryons and mesons are colorless”?

> Find the number of electrons, and of each species of quark, in 1.00 L of water.

> The quark composition of the proton is uud, whereas that of the neutron is udd. Show that the charge, baryon number, and strangeness of these particles equal the sums of these numbers for their quark constituents.

> Determine whether or not strangeness is conserved in the following decays and reactions. (a) Λ0 ( p + π- (b) π- + p ( Λ0 + K0 (c) (d) (e) (f)

> (a) Show that baryon number and charge are conserved in the following reactions of a pion with a proton: (b) The first reaction is observed, but the second never occurs. Explain these observations. (c) Could the second reaction happen if it created a th

> If the average energy released in a fission event is 208 MeV, find the total number of fission events required to operate a 100. - W light-bulb for 1.0 h.

> Which of the following processes are allowed by the strong interaction, the electromagnetic interaction, the weak interaction, or no interaction at all? (a) (b) (c) (d) (e)

> Determine which of the reactions below can occur. For those that cannot occur, determine the conservation law (or laws) that each violates. (a) (b) (c) (d) (e)

> Each of the following reactions is forbidden. Determine a conservation law that is violated for each reaction. (a) (b) (c) (d) (e)

> For the following two reactions, the first may occur but the second cannot. Explain. K0 ( π+ + π- (can occur) Λ0 ( π+ + π- (cannot occur)

> (a) Determine the muon - lepton number in the reaction μ- ( e- + v-e + vμ. (b) Determine the value of strangeness in the reaction π- + p ( Λ0 + K0.

> A radioactive sample has an activity R. For each of the following changes, indicate whether the activity would increase, decrease, or remain unchanged. Indicate your answers with I, D, or U. (a) The number of radioactive nuclei in the sample is doubled.

> (a) Determine the baryon number of the reaction p + p- ( 2(. Determine (b) The baryon number and (c) The electron - lepton number of the reaction Ω- ( Λ0 + K-.

> A neutral pion at rest decays into two photons according to π0 ( ( + ( Find the energy, momentum, and frequency of each photon.

> A photon with an energy of 2.09 GeV creates a proton – antiproton pair in which the proton has a kinetic energy of 95.0 MeV. What is the kinetic energy of the antiproton?

> A photon produces a proton – antiproton pair according to the reaction ( ( p + p-. What is the minimum possible frequency of the photon? What is its wavelength?

> A reaction that has been considered as a source of energy is the absorption of a proton by a boron - 11 nucleus to produce three alpha particles: 11H + 115B ( 3(24He) This reaction is an attractive possibility because boron is easily obtained from Earth’

> A typical uranium - 234 fission event releases 208 MeV of energy. Determine (a) The energy released per event in joules and (b) The change in mass during the event.

> Assume a deuteron and a triton are at rest when they fuse according to the reaction 12H + 13H ( 24He + 01n + 17.6 MeV Neglecting relativistic corrections, determine the kinetic energy acquired by the neutron.

> Another series of nuclear reactions that can produce energy in the interior of stars is the cycle described below. This cycle is most efficient when the central temperature in a star is above 1.6 x 107 K. Because the temperature at the center of the Sun

> Find the energy released in the fusion reaction 11H + 12H ( 23He + (

> Particles known as resonances have very short half - lives, on the order of 10-23s. Would you guess that they are hadrons or leptons? Explain.

> When a star has exhausted its hydrogen fuel, it may fuse other nuclear fuels. At temperatures above 1.0 x 108 K, helium fusion can occur. Write the equations for the following processes. (a) Two alpha particles fuse to produce a nucleus A and a gamma ray

> The proton – proton cycle responsible for the Sun’s 3.84 x 1026 W power output yields about 26.7 MeV of energy for every four protons that are fused into a helium nucleus. Determine (a) The energy in joules released during each proton – proton cycle fusi

> Suppose a deuterium – deuterium fusion reactor is designed to have a plasma confinement time of 1.50 s. Determine the minimum ion density per cubic cm required to obtain a net power output from the reactor.

> Seawater contains 3 mg of uranium per cubic meter. (a) Given that the average ocean depth is about 4 km and water covers two - thirds of Earth’s surface, estimate the amount of uranium dissolved in the ocean. (b) Estimate how long this uranium could supp

> An all - electric home uses approximately 2.00 x 103 kWh of electric energy per month. How much uranium - 235 would be required to provide this house with its energy needs for one year? Assume 100% conversion efficiency and 208 MeV released per fission.

> According to one estimate, there are 4.4 x 106 metric tons of world uranium reserves extractable at $130/kg or less. About 0.70% of naturally occurring uranium is the fissionable isotope 235U. (a) Calculate the mass of 235U in this reserve in grams. (b)

> Natural uranium ore contains about 0.720% of the fissile uranium - 235 isotope. Suppose a sample of uranium ore contains 2.50 x 1028 uranium nuclei. Determine the number of uranium - 235 nuclei in the sample.

> A piece of charcoal used for cooking is found at the remains of an ancient campsite. A 1.00-kg sample of carbon from the wood has an activity equal to 5.00 x 102 decays per minute. Find the age of the charcoal. Hint: Living material has an activity equal

> After how many half-lives will (a) 10.0%, (b) 5.00%, and (c) 1.00% of a radioactive sample remain?

> A by-product of some fission reactors is the isotope 23994Pu, which is an alpha emitter with a half-life of 24000 years: Consider a sample of 1.0 kg of pure 23994Pu at t = 0. Calculate (a) The number of 23994Pu nuclei present at t = 0 and (b) The initia

> Explain the main differences between alpha, beta, and gamma rays.

> The theory of nuclear astrophysics is that all the heavy elements like uranium are formed in the interior of massive stars. These stars eventually explode, releasing the elements into space. If we assume that at the time of explosion there were equal amo

> After the sudden release of radioactivity from the Chernobyl nuclear reactor accident in 1986, the radioactivity of milk in Poland rose to 2.00 x 103 Bq/L due to iodine - 131, with a half - life of 8.04 days. Radioactive iodine is particularly hazardous

> A medical laboratory stock solution is prepared with an initial activity due to 24Na of 2.5 mCi/mL, and 10.0 mL of the stock solution is diluted at t0 = 0 to a working solution whose total volume is 250 mL. After 48 h, a 5.0 - mL sample of the working so

> Many radioisotopes have important industrial, medical, and research applications. One of these is 60Co, which has a half - life of 5.2 years and decays by the emission of a beta particle (energy 0.31 MeV) and two gamma photons (energies 1.17 MeV and 1.33

> In a piece of rock from the Moon, the 87Rb content is assayed to be 1.82 x 1010 atoms per gram of material and the 87Sr content is found to be 1.07 x 109 atoms per gram. (The relevant decay is 87Rb ( 87Sr + e-. The half - life of the decay is 4.8 x 1010

> The 14C isotope undergoes beta decay according to the process given by Equation 29.15. Find the Q value for this process. Equation 29.15:

> A 200.0 - mCi sample of a radioactive isotope is purchased by a medical supply house. If the sample has a half - life of 14.0 days, how long will it keep before its activity is reduced to 20.0 mCi?

> Find the threshold energy that the incident neutron must have to produce the reaction: 10n + 24He ( 12H + 13H.

> A radioactive sample contains 3.50 μg of pure 11C, which has a half - life of 20.4 min. (a) How many moles of 11C are present initially? (b) Determine the number of nuclei present initially. What is the activity of the sample (c) Initially and (d) After

> A particular radioactive source produces 100. mrad of 2 - MeV gamma rays per hour at a distance of 1.0 m. (a) How long could a person stand at this distance before accumulating an intolerable dose of 1.0 rem? (b) Assuming the gamma radiation is emitted u

> Why would a fusion reactor produce less radioactive waste than a fission reactor?

> A patient swallows a radiopharmaceutical tagged with phosphorus - 32 (1532P), a β- emitter with a half - life of 14.3 days. The average kinetic energy of the emitted electrons is 7.00 x 102 keV. If the initial activity of the sample is 1.31 MBq, determin

> An x - ray technician works 5 days per week, 50 weeks per year. Assume the technician takes an average of eight x - rays per day and receives a dose of 5.0 rem/yr as a result. (a) Estimate the dose in rem per x - ray taken. (b) How does this result compa

> A “clever” technician decides to heat some water for his coffee with an x - ray machine. If the machine produces 10. rad/s, how long will it take to raise the temperature of a cup of water by 50.8 C? Ignore heat losses during this time.

> A 200. - rad dose of radiation is administered to a patient in an effort to combat a cancerous growth. Assuming all the energy deposited is absorbed by the growth, (a) Calculate the amount of energy delivered per unit mass. (b) Assuming the growth has a

> A person whose mass is 75.0 kg is exposed to a whole - body dose of 25.0 rad. How many joules of energy are deposited in the person’s body?

> In terms of biological damage, how many rad of heavy ions are equivalent to 100 rad of x - rays?

> (a) Determine the product of the reaction 37Li + 24He ( ? + n. (b) What is the Q value of the reaction?

> Complete the following nuclear reactions: (a) ? + 147N ( 11H + 178O (b) 37Li + 11H ( 24He + ?

> Natural gold has only one isotope, 19779Au. If gold is bombarded with slow neutrons, e- particles are emitted. (a) Write the appropriate reaction equation. (b) Calculate the maximum energy of the emitted beta particles. The mass of 19880Hg is 197.96675 u

> Consider two reactions: (1) n + 12H ( 13H (2) 11H + 12H ( 23He (a) Compute the Q values for these reactions. Identify whether each reaction is exothermic or endothermic. (b) Which reaction results in more released energy? Why? (c) Assuming the difference

> Why do nearly all the naturally occurring isotopes lie above the N = Z line in Figure 29.3?

> (a) Suppose 105B is struck by an alpha particle, releasing a proton and a product nucleus in the reaction. What is the product nucleus? (b) An alpha particle and a product nucleus are produced when 136C is struck by a proton. What is the product nucleus?

> One method of producing neutrons for experimental use is to bombard 37Li with protons. The neutrons are emitted according to the reaction (a) Calculate the mass in atomic mass units of the particles on the left side of the equation. (b) Calculate the ma

> Identify the unknown particles X and X’ in the following nuclear reactions: (a) X + 24He ( 1224Mg + 01n (b) 23592U + 01n ( 3890Sr + X + 201n (c) 211H ( 12H + X + X’

> A beam of 6.61 - MeV protons is incident on a target of 1327Al. Those protons that collide with the target produce the reaction (1427Si has a mass of 26.986721 u.) Neglecting any recoil of the product nucleus, determine the kinetic energy of the emergin

> A wooden artifact is found in an ancient tomb. Its carbon - 14 (146C) activity is measured to be 60.0% of that in a fresh sample of wood from the same region. Assuming the same amount of 14C was initially present in the artifact as is now contained in th

> In the decay 23490Th ( AZRa + 42He, identify (a) The mass number (by balancing mass numbers) and (b) The atomic number (by balancing atomic numbers) of the Ra nucleus.

> A 3H (tritium) nucleus beta decays into 3He by creating an electron and an antineutrino according to the reaction Use Appendix B to determine the total energy released in this reaction.

> 6628Ni (mass = 65.9291 u) undergoes beta decay to 2966Cu (mass = 65.9289 u). (a) Write the complete decay formula for this process. (b) Find the maximum kinetic energy of the emerging electrons.

> Determine which of the following suggested decays can occur spontaneously: (a) 2040Ca ( e+ + 1940K (b) 14460Nd ( 24He + 14058Ce

> Find the energy released in the alpha decay of 23892U. The following mass value will be useful: 23490Th has a mass of 234.043583 u.

> When an electron and a positron meet at low speed in empty space, they annihilate each other to produce two 0.511 - MeV gamma rays. What conservation law would be violated if they produced one gamma ray with an energy of 1.02 MeV? (a) Energy (b) Momentum

> The mass of 56Fe is 55.9349 u, and the mass of 56Co is 55.9399 u. Which isotope decays into the other and by what process?

> Complete the following radioactive decay formulas: (a) 512B ( ? + e- + v- (b) 23490Th ( 23088Ra + ? (c) ? ( 714N + e- + v-

> Identify the missing nuclides in the following decays: (a) 21283Bi ( ? + 24He (b) 3695Kr ( ? + e- + v- (c) ? ( 24He + 14058Ce

> On March 11, 2011, a magnitude 9.0 earthquake struck northwest Japan. The tsunami that followed left thousands of people dead and triggered a meltdown at the Fukushima Daiichi Nuclear Power Plant, releasing radioactive isotopes 137Cs and 134Cs, among oth

> Chromium’s radioactive isotope 51Cr has a half - life of 27.7 days and is often used in nuclear medicine as a diagnostic tracer in blood studies. Suppose a 51Cr sample has an activity of 2.00 μCi when it is placed on a storage shelf. (a) How many 51Cr nu