As the charges of identical small nuclei increase, the energy required to initia
ID: 989444 • Letter: A
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As the charges of identical small nuclei increase, the energy required to initiate nuclear fusion of them________ stays the same. decreases. Increases is proportional to their mass. is inversely proportional to their mass. What is the correct symbol for a positron?^0_-1 beta^0_1beta^1_1beta^-1_0beta^1_0beta The heaviest elements will generally have a neutron-to-proton ratio about equal to________ 0.5. 1.0. 1.3. 1.5 0.8. A half-life is________ the life that a nuclear chemist leads. the time for one-half of the unstable nuclei to decay. independent of the rate constant for decay. half of the lifetime of an unstable nucleus. constantly changing. When a positron and an electron collide, they_______ form a proton. strongly repel one another and recoil. annihilate each other and produce gamma rays. form a neutron and emit gamma rays form a neutron. Nuclear fission produces energy because_______ the total mass of the products is less than that of the reactants the total mass of the products is more than that of the reactants. it is a very powerful chemical reaction. neutrons arc produced. photons arc produced. Uranium-235 is the fuel in nuclear power plants. When a nucleus of uranium-235 captures a neutron, the nucleus splits into two lighter nuclei and initiates a chain reaction. The chain reaction is driven by the emission of________protons. positrons. neutrons. beta particles. alpha particles. Which statement about an anode in a voltaic cell is correct? Chemical species can have their oxidation number decreased at the anode. Reduction occurs at the anode Usually the anode is a bridge connects the two solutions of the cell In the external circuit, electrons flow toward the anode. Oxidation occurs at the anode. The standard reduction potentials have been determine using_______ A battery A standard hydrogen electrode A silver/silver chloride electrode A zinc air battery The work done on a circuitExplanation / Answer
(8) Correct choice is (C) since the nuclei with identical charges repel to each other. So, to over come these replusion forces more energy is required to initiate nuclear fusion.
(9) Position is a parcticle with +1 unit charge. The base number represent the charge. So, the correct choice is (B) since only it has positive base value(+1).
(10) Smaller nuclei are more stable since the neutron to proton ratio for them is around 1 where as the ratio for heavier nuclei is around 1.5. So, the correct choice is (D).
(11) Half like is the time in which the initial amount of a radioactive substance remains half. So, the correct choice is (B).
(12) we know that electron has negative charge and positron has a positive charge. When two oppositely charged particles collide, destruction takes place. This is called Annihilation. Gamma rays are formed in this process. So, the correct choice is (C).
(13) we know that, E = mc^2
where c is the speed of light and m is the mass. From first law of thermodynamics, energy could never be created nor destroyed. It could only be converted from one form to another. So, the mass could be converted into energy. If mass is converted into energy then it means mass of the products has to be less than mass of reactants.
So, the correct choice is (A).
(14) It is a nuclear fission reaction in which heavy nuceus breaks to give small nuclei. This process is initiated by the attack of neutrons.In this process new neutrons are formed that further attack on the parent nuclei and breaks it down into smaller nucei and starts a chain reaction. So, the correct choice is (C).
(15) Voltaic cell is a cell in which we take different electrons in the solutions of their electrlytes and it is used to produce electric energy by means of a chemical (redox) reaction. These two electrodes are anode and cathode. Oxidation takes place at anode and reduction takes place at cathode. Since oxidation is a process in which oxidation number increases and it takes place at anode, the first choice is incorrect.
second choice is also incorrect as reduction occurs at cathode.
anode is not a bridge to connect two solutions but a salt bridge is used to connect the two solutions via which the moment of ions takes place. So, third choice is also not correct.
Oxidation takes place at anode and in oxidation electrons are released that moves towards the cathode where reduction takes place. So, fourth choice is also not correct.
So, the correct choice is the last one, (E), Oxidation takes place at the anode.
(16) Standard reduction potentials are measured by using A standard hydrogen electrode and the reduction potential for it is taken as 0.00 V.
So, the correct choice is (B).
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