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All questions of Atomic & Nuclear Physics for UPSC CSE Exam
The atomic number of an element is determined by the number of:- a)Protons
- b)Electrons
- c)Neutrons
- d)Nucleons
Correct answer is option 'A'. Can you explain this answer?
The atomic number of an element is determined by the number of:
a)
Protons
b)
Electrons
c)
Neutrons
d)
Nucleons
|
Tarun Iyer answered |
Understanding Atomic Number
The atomic number of an element is a fundamental concept in chemistry and physics, representing the identity of an element.
Definition of Atomic Number
- The atomic number is defined as the number of protons found in the nucleus of an atom.
- It is denoted by the symbol "Z."
Significance of Protons
- Protons are positively charged particles that contribute to the atomic mass and determine the element's identity.
- Each element on the periodic table has a unique atomic number, which distinguishes it from other elements.
Relationship with Electrons
- In a neutral atom, the number of electrons equals the number of protons.
- While electrons influence chemical behavior, the atomic number strictly refers to protons.
Neutrons and Nucleons
- Neutrons are neutral particles in the nucleus and do not affect the atomic number.
- Nucleons refer to both protons and neutrons together, but only protons define the atomic number.
Conclusion
- Therefore, the correct answer to the question is option 'A': the atomic number is determined by the number of protons.
- Understanding the atomic number is crucial for studying the properties and behaviors of different elements in chemistry.
The atomic number of an element is a fundamental concept in chemistry and physics, representing the identity of an element.
Definition of Atomic Number
- The atomic number is defined as the number of protons found in the nucleus of an atom.
- It is denoted by the symbol "Z."
Significance of Protons
- Protons are positively charged particles that contribute to the atomic mass and determine the element's identity.
- Each element on the periodic table has a unique atomic number, which distinguishes it from other elements.
Relationship with Electrons
- In a neutral atom, the number of electrons equals the number of protons.
- While electrons influence chemical behavior, the atomic number strictly refers to protons.
Neutrons and Nucleons
- Neutrons are neutral particles in the nucleus and do not affect the atomic number.
- Nucleons refer to both protons and neutrons together, but only protons define the atomic number.
Conclusion
- Therefore, the correct answer to the question is option 'A': the atomic number is determined by the number of protons.
- Understanding the atomic number is crucial for studying the properties and behaviors of different elements in chemistry.
The process of spontaneous disintegration of an unstable atomic nucleus is called:- a)Fission
- b)Fusion
- c)Radioactivity
- d)Decay
Correct answer is option 'C'. Can you explain this answer?
The process of spontaneous disintegration of an unstable atomic nucleus is called:
a)
Fission
b)
Fusion
c)
Radioactivity
d)
Decay
|
Catalyst Learningacademy answered |
The process of spontaneous disintegration of an unstable atomic nucleus is called radioactivity. Fission and fusion refer to processes involving the splitting or combining of atomic nuclei, respectively. Decay is a general term for the disintegration of particles.
Which of the following is true about the conservation of momentum and energy in a nuclear reaction?- a)Momentum is conserved, but energy is not conserved
- b)Energy is conserved, but momentum is not conserved
- c)Both momentum and energy are conserved
- d)Neither momentum nor energy is conserved
Correct answer is option 'C'. Can you explain this answer?
Which of the following is true about the conservation of momentum and energy in a nuclear reaction?
a)
Momentum is conserved, but energy is not conserved
b)
Energy is conserved, but momentum is not conserved
c)
Both momentum and energy are conserved
d)
Neither momentum nor energy is conserved
|
Paradigm Institute answered |
In a nuclear reaction, both momentum and energy are conserved. This conservation is a fundamental principle in physics.
The energy released in a nuclear fission reaction is due to:- a)Conversion of mass into energy
- b)Conversion of energy into mass
- c)Breaking of chemical bonds
- d)Formation of chemical bonds
Correct answer is option 'A'. Can you explain this answer?
The energy released in a nuclear fission reaction is due to:
a)
Conversion of mass into energy
b)
Conversion of energy into mass
c)
Breaking of chemical bonds
d)
Formation of chemical bonds
|
|
Catalyst Learningacademy answered |
The energy released in a nuclear fission reaction is primarily due to the conversion of mass into energy according to Einstein's mass-energy equivalence equation (E=mc²).
The phenomenon of the emission of electrons from the surface of a metal when exposed to light is known as:- a)Photoelectric effect
- b)Compton effect
- c)Bohr effect
- d)Cherenkov effect
Correct answer is option 'A'. Can you explain this answer?
The phenomenon of the emission of electrons from the surface of a metal when exposed to light is known as:
a)
Photoelectric effect
b)
Compton effect
c)
Bohr effect
d)
Cherenkov effect
|
|
Paradigm Institute answered |
The phenomenon of the emission of electrons from the surface of a metal when exposed to light is known as the photoelectric effect. It was explained by Albert Einstein and is the basis for the understanding of quantum mechanics.
The device used to measure radioactivity is called a:- a)Geiger-Muller counter
- b)Spectrometer
- c)Barometer
- d)Voltmeter
Correct answer is option 'A'. Can you explain this answer?
The device used to measure radioactivity is called a:
a)
Geiger-Muller counter
b)
Spectrometer
c)
Barometer
d)
Voltmeter
|
|
Paradigm Institute answered |
The device used to measure radioactivity is called a Geiger-Muller counter. It detects and measures ionizing radiation.
Which of the following statements is true about an alpha particle?- a)It consists of two protons and two neutrons
- b)It has a positive charge
- c)It is emitted during radioactive decay
- d)All of the above
Correct answer is option 'D'. Can you explain this answer?
Which of the following statements is true about an alpha particle?
a)
It consists of two protons and two neutrons
b)
It has a positive charge
c)
It is emitted during radioactive decay
d)
All of the above
|
|
Paradigm Institute answered |
An alpha particle consists of two protons and two neutrons, giving it a positive charge. It is emitted during certain types of radioactive decay.
The process of combining two light atomic nuclei to form a heavier nucleus is called:- a)Fission
- b)Fusion
- c)Radioactivity
- d)Decay
Correct answer is option 'B'. Can you explain this answer?
The process of combining two light atomic nuclei to form a heavier nucleus is called:
a)
Fission
b)
Fusion
c)
Radioactivity
d)
Decay
|
|
Paradigm Institute answered |
The process of combining two light atomic nuclei to form a heavier nucleus is called fusion. Fission is the process of splitting a heavy atomic nucleus into two or more lighter nuclei.
Which of the following particles has the highest penetrating power?- a)Alpha particles
- b)Beta particles
- c)Gamma rays
- d)Neutrons
Correct answer is option 'C'. Can you explain this answer?
Which of the following particles has the highest penetrating power?
a)
Alpha particles
b)
Beta particles
c)
Gamma rays
d)
Neutrons
|
|
Catalyst Learningacademy answered |
Among the given options, gamma rays have the highest penetrating power. They require several centimeters of lead or several meters of concrete to be effectively stopped.
The unit used to measure radioactivity is:- a)Coulomb
- b)Sievert
- c)Curie
- d)Becquerel
Correct answer is option 'C'. Can you explain this answer?
The unit used to measure radioactivity is:
a)
Coulomb
b)
Sievert
c)
Curie
d)
Becquerel
|
|
Paradigm Institute answered |
The unit used to measure radioactivity is the Curie. The Becquerel is the SI unit for radioactivity, but the Curie is still commonly used.
Which of the following particles has the least penetrating power?- a)Alpha particles
- b)Beta particles
- c)Gamma rays
- d)Neutrons
Correct answer is option 'A'. Can you explain this answer?
Which of the following particles has the least penetrating power?
a)
Alpha particles
b)
Beta particles
c)
Gamma rays
d)
Neutrons
|
|
Catalyst Learningacademy answered |
Among the given options, alpha particles have the least penetrating power. They can be stopped by a sheet of paper or a few centimeters of air.
The process of radioactive decay follows a:- a)Linear pattern
- b)Exponential pattern
- c)Periodic pattern
- d)Random pattern
Correct answer is option 'B'. Can you explain this answer?
The process of radioactive decay follows a:
a)
Linear pattern
b)
Exponential pattern
c)
Periodic pattern
d)
Random pattern
|
|
Paradigm Institute answered |
The process of radioactive decay follows an exponential pattern. The rate of decay is proportional to the number of radioactive atoms present at any given time.
Which of the following is an example of a chain reaction involving nuclear fission?- a)Nuclear power generation
- b)Nuclear fusion in stars
- c)Radioactive decay
- d)None of the above
Correct answer is option 'A'. Can you explain this answer?
Which of the following is an example of a chain reaction involving nuclear fission?
a)
Nuclear power generation
b)
Nuclear fusion in stars
c)
Radioactive decay
d)
None of the above
|
|
Catalyst Learningacademy answered |
Nuclear power generation involves a chain reaction of nuclear fission, where one fission event triggers subsequent fission events in a self-sustaining manner.
The process by which a nucleus splits into two or more smaller nuclei is called:- a)Fission
- b)Fusion
- c)Radioactivity
- d)Decay
Correct answer is option 'A'. Can you explain this answer?
The process by which a nucleus splits into two or more smaller nuclei is called:
a)
Fission
b)
Fusion
c)
Radioactivity
d)
Decay
|
|
Paradigm Institute answered |
The process by which a nucleus splits into two or more smaller nuclei is called fission. Fusion refers to the process of combining nuclei, not splitting them apart.
Which of the following particles is found in the nucleus of an atom?
- a)Protons
- b)Neutrons
- c)Both (A) and (B)
- d)Positrons
Correct answer is option 'C'. Can you explain this answer?
Which of the following particles is found in the nucleus of an atom?
a)
Protons
b)
Neutrons
c)
Both (A) and (B)
d)
Positrons
|
|
Catalyst Learningacademy answered |
Neutrons are found in the nucleus of an atom. Electrons are found in the electron cloud surrounding the nucleus.
The principle of the conservation of mass-energy is described by:- a)Ohm's law
- b)Coulomb's law
- c)Newton's law of gravitation
- d)Einstein's mass-energy equivalence equation (E=mc²)
Correct answer is option 'D'. Can you explain this answer?
The principle of the conservation of mass-energy is described by:
a)
Ohm's law
b)
Coulomb's law
c)
Newton's law of gravitation
d)
Einstein's mass-energy equivalence equation (E=mc²)
|
|
Paradigm Institute answered |
The principle of the conservation of mass-energy is described by Einstein's mass-energy equivalence equation (E=mc²), which states that energy and mass are interchangeable.
The process of a radioactive isotope decaying into a stable isotope is known as:- a)Radioactive decay
- b)Nuclear fusion
- c)Nuclear fission
- d)Transmutation
Correct answer is option 'A'. Can you explain this answer?
The process of a radioactive isotope decaying into a stable isotope is known as:
a)
Radioactive decay
b)
Nuclear fusion
c)
Nuclear fission
d)
Transmutation
|
|
Catalyst Learningacademy answered |
The process of a radioactive isotope decaying into a stable isotope is known as radioactive decay. Nuclear fusion refers to the combination of atomic nuclei, nuclear fission is the splitting of atomic nuclei, and transmutation refers to the conversion of one element into another.
The mass defect in a nuclear reaction is converted into:- a)Kinetic energy
- b)Potential energy
- c)Thermal energy
- d)Light energy
Correct answer is option 'A'. Can you explain this answer?
The mass defect in a nuclear reaction is converted into:
a)
Kinetic energy
b)
Potential energy
c)
Thermal energy
d)
Light energy
|
|
Catalyst Learningacademy answered |
The mass defect in a nuclear reaction is converted into kinetic energy according to Einstein's mass-energy equivalence equation (E=mc²).
The energy levels of electrons in an atom are quantized. This means that:- a)The energy levels can take any value
- b)The energy levels are evenly spaced
- c)The energy levels can only take certain discrete values
- d)The energy levels are determined by the atomic mass
Correct answer is option 'C'. Can you explain this answer?
The energy levels of electrons in an atom are quantized. This means that:
a)
The energy levels can take any value
b)
The energy levels are evenly spaced
c)
The energy levels can only take certain discrete values
d)
The energy levels are determined by the atomic mass
|
|
Catalyst Learningacademy answered |
The energy levels of electrons in an atom are quantized, meaning they can only take certain discrete values. This is a fundamental principle in quantum mechanics.
The half-life of a radioactive substance is defined as:- a)The time taken for the substance to decay completely
- b)The time taken for half of the substance to decay
- c)The time taken for the substance to become stable
- d)The time taken for the substance to emit radiation
Correct answer is option 'B'. Can you explain this answer?
The half-life of a radioactive substance is defined as:
a)
The time taken for the substance to decay completely
b)
The time taken for half of the substance to decay
c)
The time taken for the substance to become stable
d)
The time taken for the substance to emit radiation
|
|
Catalyst Learningacademy answered |
The half-life of a radioactive substance is defined as the time taken for half of the substance to decay. It is not the time for complete decay or the time for the substance to emit radiation.
Chapter doubts & questions for Atomic & Nuclear Physics - Lucent For GK 2025 is part of UPSC CSE exam preparation. The chapters have been prepared according to the UPSC CSE exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for UPSC CSE 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
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