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A sample of radioactive material contains 1018 atoms. The half life of the material is 2 days, then the activity of the sample is- a)3.5 x 1014 Bq
- b)3.5 x 1012 Bq
- c)7 x 1011 Bq
- d)7 x 1016 Bq
Correct answer is option 'B'. Can you explain this answer?
A sample of radioactive material contains 1018 atoms. The half life of the material is 2 days, then the activity of the sample is
a)
3.5 x 1014 Bq
b)
3.5 x 1012 Bq
c)
7 x 1011 Bq
d)
7 x 1016 Bq
|
Jyoti Sengupta answered |
To find activity of the sample --->which is the rate of disintegration.
Since radioactivity comes under 1o kinetics.
[R]=k[A] [A]-->amount of initial sample 1018 atoms
Given,
Half-life=2days
K=0.693/2x24x60x60 sec
R=(0.693/2x24x60x60)x1018
R≈3.5x1012 Bq
γ (Gamma) rays are- a)Singly ionized gas atoms
- b)Electromagnetic waves
- c)Helium nuclei
- d)Fast moving electrons
Correct answer is option 'B'. Can you explain this answer?
γ (Gamma) rays are
a)
Singly ionized gas atoms
b)
Electromagnetic waves
c)
Helium nuclei
d)
Fast moving electrons
|
Prakhar Inani answered |
Since gamma rays carry energy that's why they are electromagnetic waves.
When a radioactive nucleus emits a β – particle, the mass number of the atom- a)Increases by one
- b)Decreases by one
- c)Remain the same
- d)Decreaseds by four
Correct answer is option 'C'. Can you explain this answer?
When a radioactive nucleus emits a β – particle, the mass number of the atom
a)
Increases by one
b)
Decreases by one
c)
Remain the same
d)
Decreaseds by four
|
|
Saloni Mishra answered |
C Mass no Remains same ,there is an increase of +1 unit in atomic no
The control rods in a nuclear reactor- a)Absorb neutrons
- b)Accelerate neutrons
- c)Slow down neutrons
- d)None of the above
Correct answer is option 'A'. Can you explain this answer?
The control rods in a nuclear reactor
a)
Absorb neutrons
b)
Accelerate neutrons
c)
Slow down neutrons
d)
None of the above
|
Shreya Gupta answered |
Control rods are used in nuclear reactors to control the fission rate of uranium and plutonium. They are composed of chemical elements such as boron, silver, indium and cadmium that are capable of absorbing many neutrons without themselves fissioning.
The purpose of moderator in a nuclear reactor is- a)Slow down the neutrons
- b)Absorb the neutrons
- c)Provide protecting shield.
- d)Remove heat from the reactor
Correct answer is option 'A'. Can you explain this answer?
The purpose of moderator in a nuclear reactor is
a)
Slow down the neutrons
b)
Absorb the neutrons
c)
Provide protecting shield.
d)
Remove heat from the reactor
|
|
Divyansh Kulkarni answered |
In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, ideally without capturing any, leaving them as thermal neutrons with only minimal (thermal) kinetic energy.
What is the mass-energy equivalence formula proposed by Einstein?- a) E = mc
- b) E = mc²
- c) E = m²c
- d) E = m/c²
Correct answer is option 'B'. Can you explain this answer?
What is the mass-energy equivalence formula proposed by Einstein?
a)
E = mc
b)
E = mc²
c)
E = m²c
d)
E = m/c²
|
Elite Coaching Classes answered |
The mass-energy equivalence formula proposed by Einstein is E = mc², which states that energy (E) is equal to mass (m) times the square of the speed of light (c). This principle indicates that mass can be converted into energy.
What is the purpose of carbon dating?- a) To measure the thickness of materials
- b) To determine the charge of particles
- c) To estimate the age of rocks and fossils
- d) To assess the energy levels in nuclear reactions
Correct answer is option 'C'. Can you explain this answer?
What is the purpose of carbon dating?
a)
To measure the thickness of materials
b)
To determine the charge of particles
c)
To estimate the age of rocks and fossils
d)
To assess the energy levels in nuclear reactions
|
|
Elite Coaching Classes answered |
Carbon dating is used to estimate the age of organic materials, such as rocks or fossils, by measuring the rate of decay of carbon-14, a radioactive isotope.
Which type of radiation is most effective at ionizing materials?- a) Gamma rays
- b) Alpha particles
- c) Beta particles
- d) Neutrons
Correct answer is option 'B'. Can you explain this answer?
Which type of radiation is most effective at ionizing materials?
a)
Gamma rays
b)
Alpha particles
c)
Beta particles
d)
Neutrons
|
|
Elite Coaching Classes answered |
Alpha particles are the most effective at ionizing materials due to their higher mass and charge. They can strongly affect the medium they pass through, ionizing atoms and molecules effectively.
What is the maximum number of electrons that can be accommodated in the third shell of an atom?- a) 50
- b) 8
- c) 18
- d) 32
Correct answer is option 'C'. Can you explain this answer?
What is the maximum number of electrons that can be accommodated in the third shell of an atom?
a)
50
b)
8
c)
18
d)
32
|
|
Elite Coaching Classes answered |
The maximum number of electrons that can be accommodated in the third shell is 18. This is based on the formula 2n², where n is the shell number.
The phenomenon whereby radioactive substances emit radiation is known as:- a) Nuclear fusion
- b) Nuclear fission
- c) Radioactive decay
- d) Ionization
Correct answer is option 'C'. Can you explain this answer?
The phenomenon whereby radioactive substances emit radiation is known as:
a)
Nuclear fusion
b)
Nuclear fission
c)
Radioactive decay
d)
Ionization
|
|
Elite Coaching Classes answered |
The phenomenon of radioactive substances emitting radiation is known as radioactive decay. This process occurs when unstable nuclei lose energy by emitting radiation.
How many electrons can the first shell of an atom accommodate at most?- a) 32
- b) 18
- c) 2
- d) 8
Correct answer is option 'C'. Can you explain this answer?
How many electrons can the first shell of an atom accommodate at most?
a)
32
b)
18
c)
2
d)
8
|
|
Elite Coaching Classes answered |
The first shell of an atom can accommodate a maximum of 2 electrons. This is a fundamental principle of atomic structure, reflecting the arrangement of electrons in shells.
What term is used to describe atoms of the same element that have different mass numbers?- a) Isotones
- b) Isobars
- c) Nucleons
- d) Isotopes
Correct answer is option 'D'. Can you explain this answer?
What term is used to describe atoms of the same element that have different mass numbers?
a)
Isotones
b)
Isobars
c)
Nucleons
d)
Isotopes
|
|
Elite Coaching Classes answered |
Atoms that belong to the same element but have different mass numbers are called isotopes. They have the same number of protons but a different number of neutrons.
What happens to the atomic number of an element when it undergoes beta decay?- a) It increases by one
- b) It decreases by one
- c) It remains the same
- d) It doubles
Correct answer is option 'A'. Can you explain this answer?
What happens to the atomic number of an element when it undergoes beta decay?
a)
It increases by one
b)
It decreases by one
c)
It remains the same
d)
It doubles
|
|
Elite Coaching Classes answered |
During beta decay, the atomic number of the element increases by one because a neutron is converted into a proton, resulting in a new element with one more proton in its nucleus.
What is the primary distinction between a controlled and uncontrolled chain reaction in nuclear fission?- a) Type of fission occurring
- b) Amount of energy released
- c) Speed of neutron emission
- d) Use of moderators
Correct answer is option 'D'. Can you explain this answer?
What is the primary distinction between a controlled and uncontrolled chain reaction in nuclear fission?
a)
Type of fission occurring
b)
Amount of energy released
c)
Speed of neutron emission
d)
Use of moderators
|
|
Elite Coaching Classes answered |
The primary distinction lies in the use of moderators. A controlled chain reaction uses moderators to absorb some neutrons, regulating the reaction, while an uncontrolled chain reaction leads to a rapid, explosive release of energy.
Which of the following correctly describes isobars?- a) Same number of protons but different neutrons
- b) Same mass number but different atomic numbers
- c) Same number of neutrons but different protons
- d) Same atomic number but different mass numbers
Correct answer is option 'B'. Can you explain this answer?
Which of the following correctly describes isobars?
a)
Same number of protons but different neutrons
b)
Same mass number but different atomic numbers
c)
Same number of neutrons but different protons
d)
Same atomic number but different mass numbers
|
|
Elite Coaching Classes answered |
Isobars are defined as atoms of different elements that have the same mass number but different atomic numbers. This means they have the same total number of nucleons but differ in the number of protons.
Which of the following statements is true about gamma radiation?- a) It has high ionizing power.
- b) It is deflected by electric and magnetic fields.
- c) It consists of charged particles.
- d) It consists of electromagnetic waves.
Correct answer is option 'D'. Can you explain this answer?
Which of the following statements is true about gamma radiation?
a)
It has high ionizing power.
b)
It is deflected by electric and magnetic fields.
c)
It consists of charged particles.
d)
It consists of electromagnetic waves.
|
|
Elite Coaching Classes answered |
Gamma radiation consists of electromagnetic waves, similar to X-rays and light, and is not deflected by electric and magnetic fields due to its neutral charge.
Which radioactive particle is the least penetrating?- a) Gamma rays
- b) Alpha particles
- c) Neutrons
- d) Beta particles
Correct answer is option 'B'. Can you explain this answer?
Which radioactive particle is the least penetrating?
a)
Gamma rays
b)
Alpha particles
c)
Neutrons
d)
Beta particles
|
|
Elite Coaching Classes answered |
Alpha particles are the least penetrating due to their larger mass and charge. They can be stopped by a sheet of paper or even the outer layer of human skin.
Which of the following statements about neutrons is true?- a) They are positively charged particles.
- b) They have no charge and contribute to the mass of the nucleus.
- c) They are found outside the nucleus.
- d) They are lighter than protons.
Correct answer is option 'B'. Can you explain this answer?
Which of the following statements about neutrons is true?
a)
They are positively charged particles.
b)
They have no charge and contribute to the mass of the nucleus.
c)
They are found outside the nucleus.
d)
They are lighter than protons.
|
|
Elite Coaching Classes answered |
Neutrons are uncharged particles found in the nucleus of an atom, and they contribute to the mass number (the total count of protons and neutrons) of the element.
In nuclear fission, what happens to the heavy nucleus?- a) It combines with another nucleus.
- b) It remains unchanged.
- c) It splits into two lighter nuclei.
- d) It emits gamma rays.
Correct answer is option 'C'. Can you explain this answer?
In nuclear fission, what happens to the heavy nucleus?
a)
It combines with another nucleus.
b)
It remains unchanged.
c)
It splits into two lighter nuclei.
d)
It emits gamma rays.
|
|
Elite Coaching Classes answered |
In nuclear fission, a heavy nucleus splits into two lighter nuclei when bombarded with neutrons, releasing a significant amount of energy in the process.
Which type of radiation consists of fast-moving electrons emitted from the nucleus?- a) Beta particles
- b) Gamma rays
- c) Alpha particles
- d) Neutrons
Correct answer is option 'A'. Can you explain this answer?
Which type of radiation consists of fast-moving electrons emitted from the nucleus?
a)
Beta particles
b)
Gamma rays
c)
Alpha particles
d)
Neutrons
|
|
Elite Coaching Classes answered |
Beta particles are fast-moving electrons emitted from the nucleus during radioactive decay. They differ from cathode rays, which are emitted from orbital electrons.
What is the purpose of a moderator in a nuclear reactor?- a) To absorb neutrons and control the chain reaction
- b) To increase the temperature
- c) To produce nuclear waste
- d) To emit gamma rays
Correct answer is option 'A'. Can you explain this answer?
What is the purpose of a moderator in a nuclear reactor?
a)
To absorb neutrons and control the chain reaction
b)
To increase the temperature
c)
To produce nuclear waste
d)
To emit gamma rays
|
|
Elite Coaching Classes answered |
The purpose of a moderator in a nuclear reactor is to absorb some of the neutrons emitted during fission, thus controlling the chain reaction and allowing for a steady release of energy.
What type of decay involves the emission of a particle consisting of two protons and two neutrons?- a) Alpha decay
- b) Neutron emission
- c) Gamma decay
- d) Beta decay
Correct answer is option 'A'. Can you explain this answer?
What type of decay involves the emission of a particle consisting of two protons and two neutrons?
a)
Alpha decay
b)
Neutron emission
c)
Gamma decay
d)
Beta decay
|
|
Elite Coaching Classes answered |
Alpha decay involves the emission of an alpha particle, which consists of two protons and two neutrons. This type of decay reduces the atomic number of the element.
What is the primary component of an atom that carries a positive charge?- a) Proton
- b) Electron
- c) Nucleon
- d) Neutron
Correct answer is option 'A'. Can you explain this answer?
What is the primary component of an atom that carries a positive charge?
a)
Proton
b)
Electron
c)
Nucleon
d)
Neutron
|
|
Elite Coaching Classes answered |
The primary component of an atom that carries a positive charge is the proton. It is located in the nucleus of the atom and contributes to the atomic number, which defines the element.
Which of the following is NOT a use of radioactive isotopes?- a) Thickness measurement in manufacturing
- b) Cancer treatment
- c) Tracers in medical diagnosis
- d) Fertilizer production
Correct answer is option 'D'. Can you explain this answer?
Which of the following is NOT a use of radioactive isotopes?
a)
Thickness measurement in manufacturing
b)
Cancer treatment
c)
Tracers in medical diagnosis
d)
Fertilizer production
|
|
Elite Coaching Classes answered |
Radioactive isotopes are not used in fertilizer production. Their applications include cancer treatment, medical diagnostic tracers, and thickness measurement in various manufacturing processes.
What is a common safety precaution for handling radioactive materials?- a) Exposing to sunlight
- b) Wearing cotton gloves
- c) Storing in plastic containers
- d) Use of lead shielding
Correct answer is option 'D'. Can you explain this answer?
What is a common safety precaution for handling radioactive materials?
a)
Exposing to sunlight
b)
Wearing cotton gloves
c)
Storing in plastic containers
d)
Use of lead shielding
|
|
Elite Coaching Classes answered |
A common safety precaution for handling radioactive materials is the use of lead shielding. Lead is effective at blocking various types of radiation, thus protecting personnel from exposure.
Chapter doubts & questions for Radioactivity - Physics for EmSAT Achieve 2025 is part of EmSAT Achieve exam preparation. The chapters have been prepared according to the EmSAT Achieve exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for EmSAT Achieve 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
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