NCERT Solutions | Class 12 Physics Chapter 5

NCERT Solutions | Class 12 Physics Chapter 5 | Nuclei 

CBSE Solutions | Physics Class 12

Check the below NCERT Solutions for Class 12 Physics Part-II Chapter 5 Nuclei Pdf free download. NCERT Solutions Class 12 Physics  were prepared based on the latest exam pattern. We have Provided Nuclei Class 12 Physics NCERT Solutions to help students understand the concept very well.

NCERT | Class 12 Physics Part-II

NCERT Solutions Class 12 Physics Part-II

Book:	National Council of Educational Research and Training (NCERT)
Board:	Central Board of Secondary Education (CBSE)
Class:	12th
Subject:	Physics Part-II
Chapter:	5
Chapters Name:	Nuclei
Medium:	English

Nuclei | Class 12 Physics | NCERT Books Solutions

You can refer to MCQ Questions for Class 12 Physics Chapter 5 Nuclei to revise the concepts in the syllabus effectively and improve your chances of securing high marks in your board exams.

ncert physics class 12 Question 1.

(a) Two stable isotopes of lithium \(_{ 3 }^{ 6 }{ Li } \) and \(_{ 3 }^{ 7 }{ Li } \) have respective abundance of 7.5% and 92.5%. These isotopes have masses 6.01512 u and 7.01600 u respectively. Find the atomic weight of lithium.
(b) Boron has two stable isotopes \(_{ 5}^{ 10 }{ Li } \) and \(_{5 }^{ 11 }{ Li } \) ^.Their respective masses are 10.01294 u and 11.00931 u and the atomic weight of boron is 10.811 u. Find the abundances of \(_{ 5 }^{ 10 }{ Li } \) and
\(_{5 }^{ 11 }{ Li } \)

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

(a) Atomic weight of lithium

physics class 12 chapters Question 2.

The three stable isotopes of neon :\(_{ 20}^{ 10 }{ Ne } \) and \(_{ 22}^{ 10 }{ Ne } \) have respective abundance of 90.51%, 0.27% and 9.22%. The atomic masses of three isotopes are 19.99 u, 20.99 u and 21.99 u, respectively. Obtain the average atomic mass of neon.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

physics class 12 practical Question 3.

Obtain the binding energy of a nitrogen nucleus (\(_{ 7}^{ 14 }{ N } \)) from the following data :
m_H = 1.00783 u
m_n = 1.00867 u
_mn = 14.00307 u
Give your answer in MeV.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

class 12 physics syllabus Question 4.

Obtain the binding energy of the nuclei \(_{ 26 }^{ 56 }{ Fe } \) and
in units of \(_{ 83 }^{ 209 }{ Bi} \) from the following data:
m_H =1007825u
m_n =1008665u
m (\(_{ 26 }^{ 56 }{ Fe } \))= 55.934939 u
m (\(_{83}^{209 }{ Bi} \))
Which nucleus has greater binding energy per nucleon?

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert physics class 12 solutions Question 5.

A given coin has a mass of 3.0 g. Calculate the nuclear energy that would be required to separate all the neutrons and protons from each other. For simplicity assume that the coin is entirely made of \(_{ 29 }^{ 63 }{ Cu } \) atoms (of mass 62.92960 u). The masses of proton and neutron are 1.00783 u and 1.00867 u, respectively.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

physics class 12 practical Question 6.

Write nuclear equations for :
(a) the α-decay of \(_{ 86 }^{226 }{ Ra} \)
(b) the β^–-decay of \(_{ 15 }^{ 32 }{ p } \)
(c) the β⁺-decay of \(_{ 6 }^{ 11 }{ p } \)

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert solutions for class 12 physics Chapter 13 Question 7.

A radioactive isotope has a half-life of T years. After how much time is its activity reduced to 3.125% of its original activity (b) 1% of original value ?

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

class 12 physics notes Question 8.

The normal activity of living carbon-containing matter is found to be about 15 decays per minute for every gram of carbon. This activity arises from the small proportion of radioactive \(_{ 6 }^{ 14 }{ C } \) present with the stable carbon isotope
\(_{ 12 }^{ 6 }{ C } \) When the organism is dead, its interaction with the atmosphere (which maintains the above equilibrium activity) ceases and its activity begins to drop. From the known half-life (5730 years) of \(_{ 6 }^{ 14 }{ C } \) , and the measured activity, the age of the specimen can be approximately estimated. This is the principle of \(_{ 6 }^{ 14 }{ C } \) dating used in archaeology. Suppose a specimen from Mohenjodaro gives an activity of 9 decays per minute per gram of carbon. Estimate the approximate age of the Indus-Valley civilisation.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert physics class 12 pdf Question 9.

Obtain the amount of \(_{ 27 }^{ 60 }{ Co } \) necessary to provide a radioactive source of 8.0 mCi strength. The half­ life of \(_{ 27 }^{ 60 }{ Co } \) is 5.3 years.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

physics class 12 chapters Question 10.

The half-life of \(_{ 38 }^{ 90 }{ Sr } \) is 28 years. What is the disintegration rate of 15 mg of this isotope?

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert solutions class 12 physics Nuclei Question 11.

Obtain approximately the ratio of the nuclear radii of the gold isotope \(_{ 79 }^{ 197}{ Au } \) and silver isotope \(_{47}^{107 }{ Au } \).

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

class 12 physics ncert solutions Question 12.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert physics class 12 chapters Question 13.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

Here m_N stands for the nuclear mass of the element or particle. In order to express the Q value in terms of the atomic masses, 6 m_e mass has to be subtracted from the atomic mass of \(_{6}^{11 }{ Au } \) and 5 m_e mass has to be

physics class 12 ncert book Question 14.

The nucleus \(_{ 10 }^{ 23 }{ Ne} \) decays by β~ emission. Write down the p-decay equation and determine the maximum kinetic energy of the electrons emitted. Given that:
m(\(_{ 10 }^{ 23 }{ Sr } \)) = 22.994466 u
m(\(_{ 11 }^{ 23 }{ Sr } \)) = 22.989770 u.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert solutions for class 12 physics Chapter 13 Question 15.

The Q value of a nuclear reaction A + b ⇒ C + d is defined by [Q = m_A + m_b-m_c– m_d] c² where the masses refer to nuclear rest masses. Determine from the given data whether the following reactions are exothermic or endothermic.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

class 12 physics notes Question 16.

Suppose, we think of fission of a \(_{ 26}^{ 56 }{ Fe} \) nucleus into two equal fragments, if \(_{ 13}^{ 28 }{ Al } \). Is the fission energetically possible ? Argue by working out Q of the process. Given, m (\(_{ 26}^{ 56 }{ Fe} \)) = 55.93494 u and m (\(_{ 13}^{ 28 }{ Al } \))= 27.98191

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert physics class 12 solutions Question 17.

The fission properties of \(_{ 94}^{ 239 }{ Pu} \) are very similar to those of \(_{ 92}^{ 235 }{ u} \)u. The average energy released per fission is 180 MeV. How much energy, in MeV, is released if all the atoms in 1 kg of pure
\(_{94}^{ 239 }{ Pu} \) undergo fission ?

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert solutions class 12 physics Chapter 13 Question 18.

A 1000 MW fission reactor consumes half of its fuel in 5.00 y. How much
\(_{ 92}^{ 235 }{ u} \) did it contain initially ? Assume that all the energy generated arises from the fission of \(_{92}^{ 235 }{ u} \) and that this nuclide is consumed by the fission process.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

class 12 physics practical Question 19.

How long an electric lamp of 100 W can be kept glowing by fusion of 2.0 kg of deuterium ? The fusion reaction can be taken as

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert solutions for class 12 physics Chapter 13 Question 20.

Calculate the height of Coulomb barrier for the head on collision of two deuterons. The effective radius of deuteron can be taken to be 2.0 fm.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

The initial mechanical energy E of the two deutrons before collision is given by
E = 2 K.E.

ncert physics class 12 chapters Question 21.

From the relation R = R₀ A^1/3, where R₀ is a constant and A is the mass number of a nucleus, show that nuclear matter density is nearly constant (i.e. independent of A)

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert solutions class 12 physics Nuclei Question 22.

For the β⁺ (positron) emission from a nucleus, there is another competing process known as electron capture (electron from an inner orbit, say, the K- shell, is captured by the nucleus and a neutrino is emitted).

Show that if β⁺ emission is energetically allowed, electron capture is necessarily allowed but not vice-versa

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert physics class 12 chapters Question 23.

In a Periodic Table the average atomic mass of magnesium is given as 24.312 u. The average value is based on their relative natural abundance on Earth. The three isotopes and their masses are \(_{ 12}^{ 24 }{ Mg} \) (23.98504u), ? \(_{12}^{ 25 }{ Mg} \) (24.98584) and \(_{ 12}^{ 26 }{ Mg} \) (25.98259u). The natural abundance of \(_{ 12}^{ 24 }{ Mg} \) is 78.99% by mass. Calculate the abundances of the other two isotopes.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert solutions for class 12 physics Chapter 13 Question 24.

The neutron separation energy is defined as the energy required to remove a neutron from the nucleus. Obtain the neutron separation energies of the nuclei \(_{ 12}^{ 24 }{ Ca} \) and \(_{ 13}^{ 27 }{ Al} \) from the following data :

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert physics class 12 solutions Question 25.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

class 12 physics chapters Question 26.

Under certain circumstances, a nucleus can decay by emitting a particle more massive than an α-particle. Consider the following decay processes :

(a) Calculate the Q values for these decays and determine that both are energetically possible.
(b) The Coulomb barrier height for α-particle

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

physics class 12 practical Question 27.

Consider the fission of \(_{ 92}^{ 239}{u} \) by fast neutrons. In one fission event, no neutrons are emitted and the final stable end products, after the beta-decay of the primary fragments, are \(_{58}^{ 140}{Ce} \) and \(_{44}^{ 99}{Ru} \). Calculate Q for this fission process. The relevant atomic and particle masses

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

ncert physics class 12 chapters Question 28.

Consider the D-T reaction (deuterium-tritium-fusion) given in eqn. :

(b) Consider the radius of both deuterium and tritium to be approximately 1.5 fm. What is the kinetic energy needed to overcome the Coulomb repulsion? To what temperature must the gases be heated to initiate the reaction?

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

From the equation given in the question,

m_N refers to the nuclear mass of the element given in the brackets and m_n = mass of the neutron. If in represents the atomic mass, then

class 12 physics chapters Question 29.

Obtain the maximum kinetic energy of p-particles and the radiation frequencies to y decay in the following decay scheme. You are given that
m (¹⁹⁸Au) = 197.968233 u
m (¹⁹⁸Hg) = 197.966760 u

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

The total energy released for the transformation of \(_{79}^{ 198}{Au} \) to \(_{80}^{ 198}{u} \) can be found by considering the energies of ϒ-rays. We first find the frequencies of the ϒ-rays emitted.

cbse solutions class 12 physics Question 30.

Calculate and compare the energy released by (a) fusion of 1.0 kg of hydrogen deep within the sun and (b) the fission of 1.0 kg of ²³⁵U in a fission reactor.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

physics class 12 syllabus Question 31.

Suppose India had a target of producing by 2020 AD, 200,000 MW of electric power, ten percent of which was to be obtained from nuclear power plant. Suppose we are given that, on average, the efficiency of utilisation (i.e., conversion to electric energy) of thermal energy produced in a reactor was 25%. How much amount of fissionable uranium did our country need per year by 2000 ? Take the heat energy per fission of ²³⁵U to be about 200 MeV. Avogadro’s number = 6.023 x 10²³ mol^-1.

Ncert Solutions for Class 12 Physics Chapter 13 Answer:

NCERT Physics Class 12

Class 12 Physics Chapters | Physics Class 12 Chapter 5

NCERT Solutions For Class 12 physics

NCERT Solutions | Class 12 Physics Part-I

NCERT Solutions For Class 12 Physics Part-I Chapter 1 Electric Charges And Fields
NCERT Solutions For Class 12 Physics Part-I Chapter 2 Electrostatic Potential And Capacitance
NCERT Solutions For Class 12 Physics Part-I Chapter 3 Current Electricity
NCERT Solutions For Class 12 Physics Part-I Chapter 4 Moving Charges And Magnetism
NCERT Solutions For Class 12 Physics Part-I Chapter 5 Magnetism And Matter
NCERT Solutions For Class 12 Physics Part-I Chapter 6 Electromagnetic Induction
NCERT Solutions For Class 12 Physics Part-I Chapter 7 Alternating Current
NCERT Solutions For Class 12 Physics Part-I Chapter 8 Electromagnetic Waves

NCERT Solutions | Class 12 Physics Part-II

NCERT Solutions For Class 12 Physics Part-II Chapter 1 Ray Optics And Optical Instruments
NCERT Solutions For Class 12 Physics Part-II Chapter 2 Wave Optics
NCERT Solutions For Class 12 Physics Part-II Chapter 3 Dual Nature Of Radiation And Matter
NCERT Solutions For Class 12 Physics Part-II Chapter 4 Atoms
NCERT Solutions For Class 12 Physics Part-II Chapter 5 Nuclei
NCERT Solutions For Class 12 Physics Part-II Chapter 6 Semiconductor Electronics: Materials, Devices And Simple Circuits
NCERT Solutions For Class 12 Physics Part-II Chapter 7 Communication Systems

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