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* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Any material that is made up of only one type of atom is classified as 1. 2. 3. 4. 5. an element. an isotope. a molecular substance. radioactive a gas. 0% 1 0% 2 0% 0% 3 4 0% 5 Atoms are 1. all radioactive. 2. all electrically charged particles. 3. composed of molecules. 4. mostly empty space. 5. all of these choices. 0% 1 0% 0% 0% 2 3 4 0% 5 Which of the following particles are electrically neutral? 1. 2. 3. 4. 5. Proton Electron Ion Neutron All of these choices 0% 1 0% 2 0% 0% 3 4 0% 5 The atomic number of an element is defined by the number of 1. electrons + neutrons in an atom. 2. electrons + protons in an atom. 3. neutrons in the nucleus of an atom. 4. Protons and neutrons in the nucleus of an atom. 5. protons in the nucleus of an atom. 0% 1 0% 0% 0% 2 3 4 0% 5 A nucleus with an atomic number of 30 and a mass number of 65 must have 1. 2. 3. 4. 5. 35 protons. 30 neutrons. 35 neutrons. 65 neutrons. 65 protons. 0% 1 0% 2 0% 0% 3 4 0% 5 Which of the following is true about the radiation that we are exposed to in the everyday environment? 1. Most radiation is from natural sources such as minerals in the Earth or cosmic rays. 2. Radiation originates from human sources such as fallout from nuclear weapons and contamination from nuclear power plants. 0% 1. 0% 2. Isotopes are 1. 2. 3. 4. Atoms of the same element with different numbers of electrons. Atoms with different numbers of protons. Atoms of the same element with different numbers of neutrons. All radioactive due to unstable nuclei. 0% 1 0% 0% 2 3 0% 4 Which of these forms of radiation consists of high-speed electrons 1. 2. 3. 4. Alpha Beta Gamma Neutron 0% 1 0% 0% 2 3 0% 4 Which of these is the most penetrating in common materials? 1. 2. 3. 4. Alpha Beta Gamma All of the above are equally penetrating. 0% 1 0% 0% 2 3 0% 4 Which of the following regularly releases the most radioactive material to the surroundings? 1. Coal-burning power plants. 2. Nuclear power plants. Global coal combustion annually releases 13,000 tons of radioactive uranium and thorium into the atmosphere. 0% 1 0% 2 When food is exposed to gamma radiation, the food 1. unfortunately becomes slightly radioactive. 2. doesn’t become radioactive at all. 3. will spoil faster. 4. becomes quite radioactive and should be avoided by health-conscious people. 0% 1 0% 0% 2 3 0% 4 In the nucleus of an atom, the strong nuclear force is a 1. 2. 3. 4. short-range force. long-range force. undetectable force. repulsive force. 0% 1 0% 0% 2 3 0% 4 The strong nuclear force is a very distance-sensitive attraction. When the nucleus of an atom ejects an alpha particle, the mass number of the atom 1. 2. 3. 4. reduces by 2. reduces by 4. increases by 2. increases by 4. 0% 1 0% 0% 2 3 0% 4 When the nucleus of an atom ejects a beta particle, the atomic number of that atom 1. 2. 3. 4. reduces by 1. increases by 1. reduces by 2. increases by 2. 0% 1 0% 0% 2 3 0% 4 When uranium-238 emits an alpha particle, uranium transforms into 1. 2. 3. 4. thorium-242. thorium-238. thorium-234. any of the above thorium isotopes. 0% 1 0% 0% 2 3 0% 4 When thorium-234 emits a beta particle, thorium transforms to 1. 2. 3. 4. protactinium-232. protactinium-233. protactinium-234. protactinium-235. 0% 1 0% 0% 2 3 0% 4 Compared with the mass of a proton that is bound in an atomic nucleus, the mass of a free proton is 1. the same. 2. different. Nucleons bound in a nucleus can have a different amount of energy (mass) than nucleons that are by themselves. Mass is a condensed form of energy! (E = mc2) 0% 1 0% 2 Mass of an atomic nucleus is not equal to the sum of the masses of its parts! Energy Fe is at the bottom of an “energy valley”. Has the most tightly bound and stable nucleus in existence. Energy is released during nuclear reactions. Energy source of the Sun and other stars. The fusion of 1 gram of H can release as much energy as 20 tons of coal! Also occurs during detonation of thermonuclear (hydrogen)bombs Nuclear Fusion in the Sun • 0.7% of H is converted into energy, but the Sun consumes 657 million tons of H every second. • 4 million tons of H is converted into energy every second. A source of energy harnessed by nuclear reactors and fission (atomic) bombs Nuclear Fission Reaction: Lost mass became energy released Nuclear Fusion Reaction: Lost mass became energy released E = mc2 • Any nuclear transformation that moves nuclei toward iron (Fe) releases energy. • Iron is the “nuclear sink” for all nuclear energy production in the universe.