# Important Questions for Class 12 Physics Chapter 13 Nuclear Class 12 Important Questions

## Important Questions for Class 12 Physics Chapter 13 Core Class 12 Important Questions

#### Core Class 12 Important Questions Very Brief Answer Sort

Question 1.
Electron and alpha particles have the same de-Broglie wavelength. How do their kinetic energies relate to one another?
(Delhi 2008)

Query 2.

] Please point out the rationale why heavy water is often used as a moderator in a nuclear reactor. (Delhi 2008)
Neutrons generated throughout fission decelerate in the event that they collide with the core of the identical mass. Because strange water incorporates hydrogen atoms (a mass of just about neutrons), it may be used as a moderator. Nevertheless it absorbs neutrons at a quick price via the response:

Right here, d is deutron. To overcome this problem, heavy water is used as a moderator of minor cross-section for neutron absorption.

Question three.
Identify the absorbent material used to regulate the speed of response of neutrons in a nuclear reactor. (Delhi 2008)

Question four.
State the traits of tzvo nuclear energy. (All India 2008)
(i) Nuclear energy is nature's strongest drive.
(ii) They’re saturated forces.
(iii) They’re booking unbiased.

Query 5.
Two cores have mass ratios of 1: 2. What’s the ratio of their core densities? (Delhi 2009)

Query 6
is a mass ratio of 1: 3. What is the ratio of their core densities? (Delhi 2009)
Because the core density is mass unbiased, the ratio of the core densities is 1: 1.

Question 7.
The 2 cores have the mass numbers within the ratio 2: 5. What is the ratio of their core densities? (Delhi 2009)
Core density is mass-independent, so the ratio is 1: 1.

Query eight.
The two cores have mass ratios of 1: 8. What’s the ratio of their core radii? (All India 2009)

<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796477_421_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.png" alt=" Question 9. the core has mass ratios of 8: 125. What is the ratio of their core rays? (All India 2009)

<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796476_333_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.png" alt=" Two Questions the core has mass ratios of 27: 125. What's the ratio of their core rays? (All India 2009)

Question 11.
Write two attribute options of nuclear energy. (All India 2009)
1. Nuclear power is one in every of nature's most powerful forces.
2. Nuclear energy is charge-independent.

Question 12.
What is the relationship between the decay constant of a radioactive nucleus and the typical life? (Comptt All India 2009)

#### Core Category 12 Important Questions Very Brief Reply Sort VSA-I

Query 1.
Electron and alpha particles have the identical de-Broglie wavelength as they. How do their kinetic energies relate to each other? (Delhi 2008)

Q2. why heavy water is often used as a moderator in a nuclear reactor. (Delhi 2008)
Neutrons generated throughout fission decelerate in the event that they collide with the core of the identical mass. Because abnormal water accommodates hydrogen atoms (a mass of just about neutrons), it may be used as a moderator. Nevertheless it absorbs neutrons at a fast price by way of response:

Here, d is a deutron. To overcome this problem, heavy water is used as a moderator of minor cross-section for neutron absorption.

Query 3.
Identify the absorbent material used to regulate the speed of response of neutrons in a nuclear reactor. (Delhi 2008)

Query four.
Describe two characteristics of nuclear energy. (All India 2008)
(i) Nuclear energy is nature's strongest pressure.
(ii) They’re saturated forces.
(iii) They’re reserving unbiased.

Query 5.
Two cores have mass ratios of 1: 2. What’s the ratio of their core densities? (Delhi 2008)

Question 6.
is a mass ratio of 1: three. What’s the ratio of their core densities? (Delhi 2008)
Because the core density is mass unbiased, the ratio of the core densities is 1: 1.

Question 7.
The two cores have the mass numbers in the ratio 2: 5. What is their core density ratio? (Delhi 2008)
Core density is mass-independent, so the ratio is 1: 1.

Query 8.
Two cores have mass ratios of 1: 8. What is the ratio of their core radii? (All India 2008)

<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796476_333_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.png" alt=" Two Questions the core has mass ratios of 8: 125. What is the ratio of their core rays? (All India 2008)

Kahd the core has mass ratios of 27: 125. What’s the ratio of their core rays?

<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796478_263_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.png" alt=" Important Questions for Class 12 Physics Chapter 13 Nuclear Class 12 Important Questions 12 [19659050] Question 11.
Write down two traits of nuclear energy. (All India 2008)
1. Nuclear power is one among nature's strongest forces.
2. Nuclear power is charge-independent.

Query 12.
What’s the relationship between the decay constant of a radioactive nucleus and the typical life? (Comptt. All India 2012)
The relationship between the decay constant of the radioactive nucleus and common life is

Query 13.
Write down the relationship between the dimensions of the nucleus and the atomic mass. (Comptt. All India 2012)
The connection between nucleus measurement and atomic mass is

Question 14.
Decide the exercise of a specific radioactive substance. Write down its S.I. unit. (All India 2012)
The exercise of a radioactive substance is outlined as the rate of degradation of the substance. The SI unit of activity is bekequerel (Bq).

Question 15.
How does the radius of a nucleus relate to its mass quantity A? (Comptt. All India 2012)

<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796476_333_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.png" alt=" ] Why is it troublesome to detect neutrinos in core P-decay experimentally? (All India 2012)
Detecting neutrinos in core P-degeneration is experimentally troublesome for two reasons:
(i) the mass of neutrino is extraordinarily small;
(ii)) its charge is insignificant. Neutrinos additionally interact very poorly with matter. Question 19. Identify and define the SI unit for the "activity" of a specific sample of radioactive nuclei. (Comptt. All India 2012)
(i) becquerel is the SI activity unit of a nuclear sample.
(ii) one becquerel exercise is equal to at least one degradation / degradation per second.

#### Important Questions for Class 12 Brief Reply Sort (SA-I)

Question 18

. Question 19.
Calculate the power launched by MeV within the following nuclear reaction:

(19459082) India 2012)

Query 20.
Within the Radioactive Nucleus " A "happens in a collection of decompositions in response to the following method:

The mass and atomic variety of A are 190 and 75 respectively. What are these numbers for A4? (Delhi 2016)

So Number A4 → 69
and atomic number A4 → 172

Query 21.
Within the radioactive core & # 39; A & # 39; a collection of decompositions happen based on the next diagram:

The mass and atomic variety of A are respectively 180 and 72. What are these numbers for A4?
Collection might be shown under:

So, A4 has a mass of 182
and an A4 atomic number of 72

Question 22.
(a) The mass of the nucleus at its primary state is all the time lower than the entire mass of its constituents – neutrons and protons. Clear.
(b) Draw a graph displaying the change in potential power of a pair of nucleons as a perform of their distinction. (All India 2016)
(a) As nucleons strategy each other to type a nucleus, they appeal to strongly to each other. Their potential power decreases and turns into unfavorable. It’s this potential power that holds the nucleons together in one nucleus. & # 39; The reduction of potential power leads to a decrease in the mass of nucleons inside the nucleus.

<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796476_333_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.png" alt=" Heavy core X with mass 240 and binding energy per nucleon 7.6 MeV, is divided into two fragments Y and Z of mass numbers 110 and 130. The binding energy of the Y nucleons and Z is 8.5 MeV per nucleon. Calculate the energy released per decay as Q MeV. (Delhi 2016)

∴ Bond Affirmation Nuclear Power = eight.5 – 7.6 = zero.9 MeV
Thus, the full binding power per nuclear fission = 240 × 0.9 = 216 MeV

Query 24. Draw a graph of the potential power of a pair of nucleons to separate them. Write two essential conclusions that you would be able to draw concerning the nature of nuclear energy. (All India 2016)
Two necessary conclusions:
(i) Nuclear power between two nucleons quickly drops to zero because they are various femtometers aside. This explains the steadiness of the binding power of a giant nucleus in the direction of a nucleon.

<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796481_282_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.png" alt=" Important Questions for Class 12 Physics Chapter 13 Nuclear Class 12 Important Questions 26
<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796481_282_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.png" alt=" 19659096] (ii) The diagram explains that power is engaging over 0.8 fin for distances of less than zero.8m. Question 25.
Draw a graph of bond power per nucleon as a perform of mass. for numerous nuclei, 2 ≤ A ≤ 240. How do you clarify the persistence of binding power per nucleon in the vary 30 <A <170 utilizing the property that nuclear energy is of brief range? (All India 2016)
(a) The fixed power of binding within the vary 30 <A <170 is because of the brief distance of nuclear power.
If the nucleus in a nuclear domain can have at most p neighbors, its binding power can be proportional to p. Since a lot of the giant nucleus nucleons are situated inside and never on the surface, the change in binding power per nucleon can be small. The binding power per nucleon is constant and roughly equal to that of SMEs. A property that affects solely a nucleon in its neighborhood is a nuclear saturation property.

<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796482_499_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.png" alt=" Important Questions for Class 12 Physics. Chapter 13 Nuclear Class 12 Important Issues 27 (19659098) (b) Nuclear power is a short vary giant sufficient core. The core is just underneath the affect of some of its neighbors, which fall inside the scope of nuclear energy. If a nucleon can have a maximum of P neighbors within the nuclear range, its binding power can be proportional to the & quot; P & quot; worth, so that when adding "A", including nucleons will hold the binding power fixed. Query 26
Using the curve of binding power per nucleon as a perform of mass A, clearly state how the power release in nuclear fission and fusion processes could be explained. (All India 2011)
1. Nuclear Fission: The binding power per nucleon is lower in heavier nuclei than in center nuclei, i.e. heavier nuclei are much less secure. Because the heavier nucleus breaks down into lighter nuclei, the B.E./nucleon modifications (will increase) from about 7.6 MeV to 8.four MeV. Greater binding power of product cores results in power launch. That is what happens in nuclear fission, which is the inspiration of the atomic bomb. Important Questions for Class 12 Physics Chapter 13 Nuclear Class 12 Important Questions 40 ” width=”320″ height=”174″ data-recalc-dims=”1″ data-lazy-src=”https://i1.wp.com/live.staticflickr.com/65535/48535519272_2972b9b53a_o.png?resize=320%2C174&is-pending-load=1#038;ssl=1″ class=” jetpack-lazy-image”/>

2. Nuclear Fusion: The binding power per nucleon is low for mild nuclei, i.e., much less secure. So when two mild nuclei mix to type a heavier nucleus, the upper binding power of the latter per nucleon leads to the release of power.

Query 27.
Perform the following nuclear reactions:

(Comptt. Delhi 2011)
<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796482_333_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.png" alt=" Important Questions for Class 12 Physics Chapter 13 Nuclear Class 12 Important Questions 30
<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796482_333_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.png" alt=" If in a nuclear response each the number of protons and neutrons remain, how does the mass grow to be power (or vice verse)? Clarify one example. (Comptt. Delhi 2011)
Rationalization of Power Launch in Nuclear Response: Because the proton quantity and neutron number stay in the nuclear response, the entire resting weight of neutrons and protons is identical in both the left aspect does not need the identical binding power. The distinction in binding power causes the release of power in the reaction.
Examples:

Essential Questions for Class 29

(Delhi 2016).

Calculate Power in a Fusion Reaction
] Important Questions for Class 12 Physics Chapter 13 Core Class 12 Important Questions 34 ” width=”296″ height=”82″ data-recalc-dims=”1″ data-lazy-src=”https://i1.wp.com/live.staticflickr.com/65535/48535367111_d0db8729f2_o.png?resize=296%2C82&is-pending-load=1#038;ssl=1″ class=” jetpack-lazy-image”/>

(Delhi 2016)

## Reply: Question 31. If the number of both protons and neutrons in every nuclear response is retained, how is the mass converted to power (or vice versa) ? Clarify. (Comptt. All India 2016) Answer: The number of protons and neutrons in the nuclear reaction is preserved but the complete mass shouldn’t be conserved. The entire mass of free protons and neutrons is bigger than their complete mass in the nucleus. The misplaced mass (= ∆m), generally known as the “mass deficiency”, is converted into power within the ratio E = (∆m) c2 (c is the velocity of light). Question 32. Write two properties of nuclear power. (b) Draw a graph of the potential power of a pair of nucleons as a perform of their difference. (Comptt. All India 2017) Answer: (a) Nuclear. Robust attraction forces that maintain together nucleons (neutrons and protons) in a small nucleus of an atom are referred to as nuclear forces. Nuclear forces are charge-independent (these operate between a pair of neutrons, a pair of protons, and between a proton and a neutron). 2. Nuclear power is the strongest drive in nature. 3. Nuclear power is a really brief range drive. four. Nuclear energy is a non-central pressure. 5. Nuclear energy depends on spin. (B) The diagram exhibits the potential power between two nucleons as a perform of distance. Important Conclusions from the Scheme: (i) Nuclear energy is rather more appearing Coulomb pressure or gravity plenty. The binding pressure of nuclear energy should control the Coulomb rupture pressure between the protons contained in the nucleus. This is solely because nuclear power is far stronger than coulomb power. Gravity is far weaker than even Coulomb's. (ii) Nuclear energy between two nucleons rapidly drops to zero because their distance is various femtometers. This leads to saturation of forces with a medium or giant nucleus, which is the rationale for the persistence of the binding power per nucleon. (Iii) The nuclear power between the neutron neutron, proton neutron and proton proton is approximately the same. Nuclear power does not rely upon the electrical charge. Query 33. Write the connection between the half-life of a radioactive nucleus and the decay price. (Comptt. All India 2017) Reply: Query 34. ” width=”358″ height=”229″ data-recalc-dims=”1″/> ] The two radioactive samples, X, Y, have the same number of atoms at t = zero. Their half-lives are 3h and 4h, respectively. Examine the decay fee of the two cores after 12 hours. (Comptt All India 2017) Answer: Question 35. Separate nuclear fission and fusion. Explain how power is launched in both processes. (Comptt. All India 2017) Reply: In nuclear fission, the heavy nucleus breaks down into smaller nuclei with power launch; whereas in nuclear fusion, two mild nuclei combine to type a heavier core with power launch. In each instances, some mass (= mass failure) turns into power with respect to:

#### Important Questions Brief Reply Sort SA-II

Question 36.
Draw a graph displaying the variation in binding power per nucleon with respect to mass number (A). Use this graph to elucidate the release of power in nuclear fission and fusion processes. (All India 2009)
1. Nuclear Fission: The binding power per nucleon is decrease in heavier nuclei than in middle nuclei, i.e. heavier nuclei are much less secure. Because the heavier nucleus breaks down into lighter nuclei, the B.E./nucleon modifications (will increase) from about 7.6 MeV to 8.four MeV. Larger binding power of product cores results in power launch. This is what happens in nuclear fission, which is the inspiration of the atomic bomb. Important Questions for Class 12 Physics Chapter 13 Nuclear Class 12 Important Questions 40 ” width=”320″ height=”174″ data-recalc-dims=”1″ data-lazy-src=”https://i1.wp.com/live.staticflickr.com/65535/48535519272_2972b9b53a_o.png?resize=320%2C174&is-pending-load=1#038;ssl=1″ class=” jetpack-lazy-image”/>

2. Nuclear Fusion: The binding power per nucleon is low for mild nuclei, i.e., much less secure. So when two mild nuclei combine to type a heavier nucleus, the higher binding power of the latter per nucleon leads to the discharge of power. Query 19. Define the exercise of a radionuclide. Write down its S.I. unit. Present a graph of the exercise of the radioactive species over time.
How lengthy does it take for a radioactive isotope with a half-life of T to scale back it to 1/eight of its unique value? (All India 2009)
Exercise: It is defined as the full decay fee of a number of radionuclide samples. Its SI unit is bequerel
I bequerel = 1 degeneration per second.

<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796476_333_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.png" alt=" (i) Define & # 39; ;
(ii) Draw a graph showing the change in activity of a given radioactive sample over time. (Iii) The sequence of stepwise decay of a radioactive nucleus is

If the D2 atomic quantity and mass are 71 and 176, what are the corresponding v D?
Activity: It’s outlined as the whole decay fee of one or more radionuclide samples.
Its SI unit is bequerel
I bequerel = 1 decay per second

question 39.
(a) Write symbolically P “

.
(b) Derive an indication of the average lifetime of a radionuclide. Give its relation to the half-life. (All India 2009)

(b) the sample has the N0 core at time t = 0. Over time, this number decreases to N. In addition, suppose that the dN cores decay over time t to t + dt. Because dt is small, the age of each dN core can be estimated to be equal to t
kokonais total age of dN cores = tdN

Question 40.
State the Law of Radioactive Decay. Draw a graph showing the surface as a function of the number of unbroken nuclei for a given radioactive sample with a half-life T1 / 2. The figure should describe the number of unbroken nuclei at
(i) t = 3 T1 / 2 and
(ii) t = 51/2 (DeIhi 2009)
The cores that undergo decay per unit time are proportional to the number of inches in the sample at that instant. The given image has a graph that is truncated between the number of truncated darkers as a function of time.

Question 41.
(i) What is the characteristic of nuclear power? (BE / A) in the mass mass range A, which is 30 <A <170?
(ii) Prove that the density of the nucleus over a wide range of nuclei is constant regardless of mass number A. (Delhi 2009)
(i) Saturation is the nature of the short range of nuclear power. (Ii) Let A be the number of mass and R be the radius of the nucleus. If m is the average mass of the nucleon then
is the mass of the nucleus = mA

Clearly, nuclear density is independent of mass number A or the size of the nucleus.

Question 42.
Draw a plot of potential energy of a pair of nucleons as a function of their separations. Mark the regions where the nuclear force is
(i) attractive and
(ii) repulsive. Write any two characteristic features of nuclear forces.
The graph indicates that the attractive force between the two nucleons is strongest at a separation r0 = 1 fm. For a separation greater than the force is attractive and for separation less than r0, the force is strongly repulsive.

Two characteristic features of nuclear forces :
1. Strongest interaction
2. Short-range force
3. Charge independent character (any two)

Question 43.
(i) Why is the binding energy per nucleon found to be constant for nuclei in the range of mass number (A) lying between 30 and 170?
(ii) When a heavy nucleus with mass number A = 240 breaks into two nuclei, A = 120, energy is released in’ the process.
(iii) In β-decay, the experimental detection of neutrinos (or antineutrinos) is found to be extremely difficult. (Comptt. All India 2011)
(i) Nuclear forces are short ranged. For a particular nucleon inside a sufficiently large nucleus will be under the influence of some of its neighbours which come within the range of the nuclear force. The property that a given nucleon influences only nucleons close to it is also referred to as saturation property of the nuclear force.
(ii) The binding energy per nucleon of the parent nucleus is less than those of the two daughter nuclei. It is this increased binding energy that gets released in this process.
(iii) Neutrinos are chargeless and massless particles, whose interaction with other particles is almost negligible. Hence, they can pass through very large quantity of matter with-out getting detected.

Question 44.
(a) In a typical nuclear reaction, e.g.

although number of nucleons is conserved, yet energy is released. How? Explain.
(b) Show that nuclear density in a given nucleus is independent of mass number A. (Delhi 2011)
(a) In all types of nuclear reactions, the law of conservation of number of nucleons is followed. But during the reaction, the mass of the final product is found to be slightly less than the sum of the masses of the reactant components. This difference in mass of a nucleus and its constituents is called mass defect. So, as per mass energy relation E = (∆M)c2, energy is released. In the given reaction the sum of the masses of two deutrons is more than the mass of helium and neutron. Energy equivalent of mass defect is released.

Question 45.

though the conserved on both sides of the reaction, yet the energy is released. How? Explain.
(b) Draw a plot of potential energy between a pair of nucleons as a function of their separation. Mark the regions where potential energy is
(i) positive and
(ii) negative. (Delhi 2011)
(a) Since the total binding energy of nuclei on the left side of the reaction is not the same as the total binding energy of nucleus on the right hand side, this difference of binding energy appears as the energy released.

For separation (r) ≤ 0.8 fermi
Force is repulsive
For r > 0.8 fermi force will be attractive.

Question 46.
(a) The number of nuclei of a given radioactive sample at time t = 0 and t = T are N0 and N0/n respectively. Obtain an expression for the half-life (T1/2) of the nucleus in terms of n and T.
(b) Write the basic nuclear process underlying β-decay of a given radioactive nucleus. (Comptt. Delhi 2013)
(a) Decay constant. It is the reciprocal of the time interval in which the number of active nuclei in a radioactive sample reduces to 1/e times of its initial nuclei.
Half life period. It is the time during which half the total number of atoms in radioactive elements (N0) disintegrates. It is denoted by t1/2.

(b) β-decay. It is the phenomenon of emission of an electron from a radioactive nucleus. In Beta-minus decay, a neutron transforms into a proton within the nucleus. According to

The emission of β-particle from an atom will change it into a new atom whose atomic number is increased by one without changing its mass number.

Question 47.

(Delhi 2014)
(a) Radioactive decay law. It states that “the number of atoms disintegrated per second at any instant is directly proportional to the number of radioactive atoms actually present at that time.” Let N0 be the whole number of atoms present at time t = zero (initially)
and N be the full variety of atoms present at time t, then
In accordance with radioactive decay regulation, the rate of disintegration at any time t is immediately proportional to the variety of atoms current at that time t.

(ii) Since new nucleus has the identical mass quantity, therefore it might be an Isobar.

Question 48.
Write the relation for binding power (BE) (in MeV) of a nucleus of <img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796488_797_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.php" alt="_Z^A N" title="_Z^A N" class="latex jetpack-lazy-image" data-lazy-src="//s0.wp.com/latex.php?latex=_%7BZpercent7Dpercent5E%7BApercent7D+N&is-pen ding-load=1#038;bg=ffffff&fg=000&s=0" />

<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796488_797_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.php" alt="_Z^A N" title="_Z^A N" class="latex"/>, atomic number (Z) and mass quantity (A) when it comes to the plenty of its constituents – neutrons and protons.
(b) Draw a plot of BE/A versus mass quantity A for 2 ≤ A ≤ 170. Use this graph to elucidate the discharge of power within the means of nuclear fusion of two mild nuclei. (Comptt. Delhi 2014)
(a) Mass defect. The difference between the sum of the plenty of neutrons and protons forming a nucleus and mass of the nucleons known as mass defect.

(b)

Conclusions :
(i) The drive is engaging and sufficiently robust to supply a binding power of a few MeV per nucleon.

(b) (i) Once we transfer from heavy nuclei area to center region, we find that there shall be a achieve in ove rall binding power and therefore launch of power. This indicates that power may be launched when a heavy nucleus breaks into two roughly equal fragments/nuclear fission.
(ii) Similarly, once we move from lighter nuclei to heavier nuclei, we find that there shall be achieve in general binding power and hence release of power. This means that power might be launched when two lighter
nuclei fuse together to type heavy nucleus/nuclear fusion.
(c) In Beta decay a neutron breaks right into a proton, electron and neutrino as

Detection of neutrinos is troublesome as a result of they are chargeless and have either no or low mass.

Query 49.
(a) Outline the time period ‘activity of a sample of radioactive nucleus. Write its S.I. unit.

(Comptt. All India 2014)
(a) The activity of a radioactive nucleus equals its decay rate (or number of nuclei decaying per unit time)

Question 50.
(i) Write the relation between ‘average life’ and ‘half-life’ of a radioactive nucleus.

(Comptt. All India 2014)

Query 51.
(i) Define the time period ‘mass defect’ of a nucleus. How is it related with its binding power?
(ii) Determine the Q-value of the following response:

(Comptt. All India 2014)
(i) (a) The mass defect of a nucleus equals the distinction between the entire mass of its constituents and the mass of the nucleus itself.

Question 52.
Distinguish between nuclear fission and fusion. Show how in each these processes power is released.
Calculate the power launch in MeV within the deuterium-tritium fusion reaction :

(Delhi 2015)
(a) The breaking of heavy nucleus into smaller fragments known as nuclear fission; whereas the joining of lighter nuclei to type a heavy nucleus is known as nuclear fusion.
(b) Binding power per nucleon of the daugher nuclei, in each processess, is greater than that of the mum or dad nuclei. The difference in binding power is released in the form of power. In each processes some mass gets converted into power.
(c) Power released

Question 53.
(a) Write three attribute properties of nuclear pressure.
(b) Draw a plot of potential power of a pair of nucleons as a perform of their separation. Write two essential conclusions that can be drawn from the graph. (All India 2015)
(a) Nuclear forces. The robust forces of attraction which hold together the nucleons (neutrons and protons) in the tiny nucleus of an atom are referred to as nuclear forces.
Important properties (characteristics):
1. Nuclear forces are unbiased of charge (These act between a pair of neutrons, between a pair of protons and between a proton and a neutron).
2. Nuclear forces are the strongest forces in nature.
3. Nuclear forces are very brief range forces.
four. Nuclear forces are non-central forces.
5. Nuclear forces are depending on spin.

(b) A plot of the potential power between two nucleons as a perform of distance is proven within the diagram.

Important conclusions from the graph :
(i) The nuclear drive is far stronger than the Coulomb pressure appearing between fees or the gravitational forces between plenty. The nuclear binding drive has to dominate over the Coulomb repulsive pressure between protons contained in the nucleus. This happens solely because the nuclear drive is far stronger than the coulomb pressure. The gravitational pressure is far weaker than even Coulomb pressure.
(ii) The nuclear drive between two nucleons falls quickly to zero as their distance is various femtometers. This leads to saturation of forces in a medium or a large-sized nucleus, which is the rationale for the constancy of the binding power per nucleon.
(iii) The nuclear drive between neutron- neutron, proton-neutron and proton-proton is approximately the same. The nuclear drive does not rely upon the electrical cost.

Question 54.
Full the following nuclear reactions :

(c) Why is it found experimentally troublesome to detect neutrinos? (Comptt. All India 2017)

It is discovered experimentally troublesome to detect neutrinos in nuclear P-decay, due to two causes :
(i) mass of neutrino is extraordinarily small;
(ii) its cost is negligibly small.
Additionally, neutrinos work together very weakly with matter.

Question 55.
(a) Write the essential nuclear process concerned within the emission of β+ in a symbolic type, by a radioactive nucleus.
(b) Within the reactions given under :

Discover the values of x, y, and z and a, b and c. (All India 2017)

Question 56.
Acquire the relation <img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796493_606_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.php" alt="mathbfN=mathbfN_0 e^-lambda t" title="mathbfN=mathbfN_0 e^-lambda t" class="latex jetpack-lazy-image" data-lazy-src="//s0.wp.com/latex.php?latex=%5Cmathbfpercent7BN%7D%3D%5Cmathbfpercent7BN%7D_percent7B0%7D+epercent5Epercent7B-%5Clambda+tpercent7D&is-pending-load=1#038;bg=ffffff&fg=000&s=zero" />

<img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796493_606_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.php" alt="mathbfN=mathbfN_zero e^-lambda t" title="mathbfN=mathbfN_zero e^-lambda t" class="latex"/> for a sample of radioactive material having decay fixed λ, the place N is the variety of nuclei present at c onstant λ. Therefore acquire the relation between decay constant λ and half life <img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796493_878_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.php" alt="mathbfT_frac12" title="mathbfT_frac12" class="latex jetpack-lazy-image" data-lazy-src="//s0.wp.com/latex.php?latex=%5Cmathbfpercent7BTpercent7D_percent7Bpercent5Cfrac%7B1percent7Dpercent7B2percent7Dpercent7D&is-pending-load=1#038;bg=ffffff&fg=000&s=0" /><img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796493_878_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.php" alt="mathbfT_frac12" title="mathbfT_frac12" class="latex"/> of the pattern. (Comptt. Delhi 2017)
(i)
(a) Radioactive decay regulation. It states that “the number of atoms disintegrated per second at any instant is directly proportional to the number of radioactive atoms actually present at that time.” Let N0 be the entire variety of atoms present at time t = 0 (initially)
and N be the full variety of atoms current at time t, then
In line with radioactive decay regulation, the speed of disintegration at any time t is immediately proportional to the variety of atoms current at the moment t.

(ii) Relation between X and <img src="https://thecrockettreporter.com/wp-content/uploads/2019/08/1565796493_878_important-questions-for-class-12-physics-chapter-13-nuclear-class-12-important-questions.php" alt="mathbfT_frac12" title="mathbfT_frac12" class="latex jetpack-lazy-image" data-lazy-src="//s0.wp.com/latex.php?latex=%5Cmathbf%7BTpercent7D_percent7Bpercent5Cfrac%7B1percent7Dpercent7B2percent7Dpercent7D&is-pending-load=1#038;bg=ffffff&fg=000&s=zero" />$mathbfT_frac12$
After one hal f life, Number of nuclei becomes

Question 57.
(i) A radioactive nucleus ‘A’ undergoes a collection of decays as given under:

The mass quantity and atomic number of A2 are 176 and 71 respectively.
Decide the mass and atomic numbers of A4 and A.

(Delhi 2017)

Query 58.
(a) Draw a graph displaying the variation of binding power per nucleon (BE/A) vs mass quantity A for the nuclei in 20 ≤ A ≤ 170.
(b) A nucleus of mass number 240 and having binding power/nucleon 7.6 MeV splits into two fragments Y, Z of mass numbers 110 and 130 respectively. If the binding power/ nucleon of Y, Z is the same as 8.5 MeV every, calculate the power launched in the nuclear response. (Comptt. All India 2017)

Conclusions :
(i) The pressure is engaging and sufficiently robust to supply a binding power of some MeV per nucleon.

#### Nuclei Class 12 Important Questions Long Brief Reply Sort

Question 59.
(a) Define the term ‘activity’ of a given pattern of radionuclide. Write the expression for the regulation of radioactive decay when it comes to the activity of a given pattern.
(b) A radioactive isotope has a half life of T years. How lengthy will it take the exercise to scale back to 3.125% of its unique worth?
(c) When a nucleus (X) undergoes β-decay, and transforms to the nucleus (Y), does the pair (X, Y) type isotopes, isobars or isotones? Justify your answer. (Comptt. Delhi 2012)
(a) The exercise of a radioactive supply is measured by the speed of disintegration of the source. It’s denoted by ‘A’

Query 60.
(a) Draw the plot of binding power per nucleon (BE/A) as a perform of mass quantity A. Write two necessary conclusions that may be drawn relating to the nature of nuclear drive.
(b) Use this graph to elucidate the release of power in each the processes of nuclear fusion and fission.
(c) Write the essential nuclear strategy of neutron present process β-decay. Why is the detection of neutrinos discovered very troublesome?

Conclusions :
(i) The pressure is engaging and sufficiently robust to supply a binding power of some MeV per nucleon.

(b) (i) Once we transfer from heavy nuclei region to middle region, we discover that there might be a achieve in general binding power and hence launch of power. This indicates that power may be launched when a heavy nucleus breaks into two roughly equal fragments/nuclear fission.
(ii) Equally, once we move from lighter nuclei to heavier nuclei, we find that there might be achieve in general binding power and therefore release of power. This indicates that power may be released when two lighter
nuclei fuse together to type heavy nucleus/nuclear fusion.
(c) In Beta decay a neutron breaks into a proton, electron and neutrino as

Detection of neutrinos is troublesome as a result of they’re chargeless and have either no or low mass.