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Energy Engineering Multiple Choice Questions on “Nuclear Fission & Nuclear Fusion”.
1. In which of the following process are Neutrons emitted?
A. Inverse beta Decay
B. Nuclear fission
C. Spontaneous Fission
D. Nuclear fusion
Answer: B
clarification: Nuclear fission is the process in which a heavy nucleus is split into two or more lighter nuclei. This result in decrease in mass and consequent exothermic energy and emission of neutrons take place. Two to three neutrons are emitted per nucleuses which are known as fission elements.
2. Heavy nuclei must be such that they can be fissioned by neutrons of an energy such substance are called?
A. Fission fragments
B. Fission Neutrons
C. Fission species
D. Fission elements
Answer: C
clarification: Heavy nuclei must be such that they can be fissioned by neutrons of energy such substance are called Fission species. All fission species should have long half lives so that the rate of decay is not so fast.
3. Why neutrons with lower energy should be capable of causing fission?
A. For faster reaction process
B. For sustained reaction process
C. For Safety purpose
D. In order to not waste the nuclear fuel
View Answer
Answer: B
clarification: Due to collisions with various nuclei, initial high kinetic energy of fission neutron decreases. Thus for a sustained reaction, eve neutrons with lower energy should be capable of causing fission. Only neutrons can result in sustained reaction as two or three neutrons are released for each one absorbed by fission.
4. What happens when a neutron is absorbed by a nucleus of an atom of U235?
A. Mass number of atom increases
B. One electron is let out
C. U236 isotope is formed
D. Nucleus becomes unstable
Answer: C
clarification: When a neutron is absorbed by a nucleus of an atom U235, a U236 isotope is formed. This isotope is highly unstable which lasts for one millionth of a second and splits into two equal parts releasing energy of 200MeV.
5. Who invented nuclear fission?
A. Rutherford
B. Hans Bethe
C. Otto Hahn
D. Marie Curie
Answer: C
clarification: Nuclear fission of heavy metals was discovered by German Otto Hahn on December 17, 1938 and was explained theoretically by Lise Meitner and her nephew Otto Robert Frisch on 1939. Frisch named Frisch names the process by analogy with biological fission of living cells.
6. Atoms of different chemical elements that have the same number of nucleons are called as?
A. Isobars
B. Isotones
C. Isomers
D. Isotopes
Answer: A
clarification: Atoms of different chemical elements that have the same number of nucleons are called as isobars. The term isobar was suggested by Alfred Walter Stewart in 1918. It is derived from Greek word ‘isos’ meaning EQUAL and ‘baros’ meaning WEIGHT.
7. Most of the energy released in fission process is in process of __________
A. Kinetic Energy
B. Thermal Energy
C. Light Energy
D. Heat Energy
Answer: A
clarification: Most of the energy released is in the form of kinetic energy and is absorbed by fission products. The fission products formed are fission fragments, neutrons and electromagnetic or gamma radiation. As the fragments collide, the kinetic energy is converted into heat energy.
8. Combining of two light nuclei of low mass to produce a heavy nucleus is called ___________
A. Nuclear fusion
B. Nuclear fission
C. Spontaneous fission
D. Double beta decay
View Answer
Answer: A
clarification: Nuclear fusion is the process which involves fusion of two light nuclei of low mass to produce a heavy nucleus which results in decrease of mass and release of enormous amount of energy. All atomic bombs prefer nuclear fission process.
9. What type of Reaction takes place in sun?
A. Nuclear fusion
B. Nuclear fission
C. Spontaneous fission
D. Double beta decay
Answer: A
clarification: Nuclear fusion reaction takes place in sun as well as stars. The process is carried by proton-proton chain. The sun starts with protons, and through a series of steps, turns them into helium. Every second 600 million tons of hydrogen is converted into helium. The reaction releases tremendous amount of heat and energy.
10. How many number of nuclei of hydrogen fuse in a series of reaction involving other particles that continually appear and disappear?
A. 1
B. 2
C. 3
D. 4
View Answer
Answer: D
clarification: Four nuclei of hydrogen fuse in a series of reaction involving other particles that continually appear and disappear such as He3, nitrogen, carbon and other nuclei.
41H1 → 2He4 + 2+1e0 (Positrons)
Mass decreases to about 0.0276amu releasing 25.7MeV. The heat liberated during this result in temperature of the order of the million degrees and sustains the succeeding reactions.
11. Why is it necessary to accelerate positively charged nuclei to high kinetic energies to cause fusion?
A. To overcome electrical repulsive forces
B. To result in high amount of energy in short period of time
C. To get the isobars and isotopes
D. To get a sustainable reaction
Answer: A
clarification: To cause fusion, it is necessary to accelerate positively charged nuclei to high kinetic energies to overcome electrical repulsive forces. This is done by rising their temperatures to hundreds of millions of degree resulting in plasma.
12. Fusion reactions are called __________
A. Thermonuclear
B. Thermoduric
C. Thermo Uric
D. Compound reactions
Answer: A
clarification: To eradicate repulsive forces temperature of positively charged nuclei is raised to millions of degree resulting in plasma. The plasma should be prevented from contacting the walls of the container confined for a period of time of the order of a second at a minimum density. Fusion reactions are called thermonuclear because of the higher temperature requirement to trigger and sustain the reaction.
13. Which of the following element is readily available in the ordinary water?
A. Cesium
B. Thorium
C. Deuterium
D. Astatine
View Answer
Answer: C
clarification: Deuterium used in fusion reaction is readily available in ordinary water (Out of 6500 molecules). Deuterium is also known as heavy hydrogen. The nucleus of deuterium is called as deuteron, Contains one proton and one neutron.
14. How is tritium made from sea water?
A. By bombarding lithium
B. By bonding with carbon
C. By bombarding Beryllium
D. By reacting with oxygen
Answer: A
clarification: Tritium is made by seawater by bombarding with lithium. Lithium is a chemical element with Atomic number: 3 and Mass number: 6.941 u ± 0.002 u. Because of its relative nuclear instability, lithium is less common in the solar system.