12th Physics weekly Test - 3 ( Atomic and Nuclear physics )

St. Britto Hr. Sec. School - Madurai

12th Physics weekly Test - 3 ( Atomic and Nuclear physics )-Aug 2020

Time : 1.30 Hours

Part - A

Multiple Choice Question - Answer All Question

The charge of cathode rays is

positive
negative
neutral
not defined

Wave number is defined as the number of wave

produced in one second
in a distance of 1 metre
in a distance of 3 x 10⁸ m
in a distance of \(\lambda\) metre

Controlled chain reaction is seen in ______

atom bombs
nuclear reactors
synchrotron
detectors

Positively charged radioactive rays are called _____ rays.

\(\alpha\)
\(\beta\)
\(\gamma\)
neutral

The first nuclear reactor was built at _________

Newyork
San Fransisco
New Jersey
Chicago

In a discharge tube, the source of positive rays is

cathode
anode
gas atoms present in the discharge tube
fluorescent screen

In J.J. Thomson e/m experiment, a beam of electron is replaced by that of muons (particle with same charge as that of electrons but mass 208 times that of electrons). No deflection condition is achieved only if
B is increased by 208 times

B is decreased by 208 times

B is increased by 14.4 times

B is decreased by 14.4 times
For first order X-ray diffraction, the wavelength in of the X-ray is equal to the lattice spacing at a glancing angle is
15°

60°

45°

30°

In the nuclear reaction ₄Be⁹ + X \(\rightarrow\) ₆C¹² + ₀n¹ X stands for

proton
\(\alpha\) particle
electron
deutron

Radioactive materials are kept in thick-walled ______ containers.

aluminium
iron
brick
lead

The ground state energy of hydrogen atom is 13.6 eV. The energy needed to ionize H₂ atom from its second excited state.

1.51 eV
3.4 eV
13.6 eV
none

Curie is a unit of

half life
intensity of nuclear radiation
energy of nuclear radiation
radioactivity

The direction of deflection shows that cathode rays are ___ in charge.

negative
positive
neutral
oscillatory

Which of the following is not a moderactor?

liquid sodium
ordinary water
graphite
heavy water

An oil drop carrying a charge q has a mass m kg. It is falling freely in air with terminal speed v. The electric field required to make the drop move upwards with the same speed is

\(\frac{mg}{q}\)
\(\frac{2mg}{q}\)
\(\frac{mgv}{q^2}\)
\(\frac{2mgv}{q}\)

Atomic number of H-Iike atom with ionization potential 122.4 V for n = 1 is

J.J. Thomson's experiment demonstrated that

cathode rays are streams of negatively charged ions
all the mass of an atom is in the nucleus
specific charge of electrons is much greater than the protons.
e/m ratio changes when different gases is placed in the discharge tube

Assertion : Electrons in the atom are held due to coulomb forces.
Reason : The atom is stable only because the centripetal force due to coulomb's law is balanced by the centrifugal force.

Assertion and Reason are correct and Reason is the correct explanation of Assertion.
Assertion and Reason are true but Reason is the false explanation of the Assertion.
Assertion is true but Reason is false.
Assertion is false but Reason is true.

\(\alpha\)-rays consist of \(\alpha\)-particles, which are ___ nuclei.

hydrogen
helium
heavy water
boron

A system consists of N₀ nucleus at t = 0. The number of nuclei remaining after half of a half-life (that is, at time t = \(\frac { 1 }{ 2 } { T }_{ \frac { 1 }{ 2 } }\))

\(\frac { { N }_{ 0 } }{ 2 } \)
\(\frac { { N }_{ 0 } }{ \sqrt { 2 } } \)
\(\frac { { N }_{ 0 } }{ 4 } \)
\(\frac { { N }_{ 0 } }{ 8 } \)

Assertion : Electron capture occurs more often than positron emission in heavy elements..
Reason : Heavy elements exhibit radio activity.

Assertion and Reason are correct and Reason is the correct explanation of Assertion.
Assertion and Reason are true but Reason is the false explanation of the Assertion.
Assertion is true but Reason is false.
Assertion is false but Reason is true.

A radiation of a particular wavelength is called a ____.
spectral line

frequency

wavelength

velocity
Natural uranium consists of _________ % of U²³⁵ and _________ % of U²³⁸.
0.72, 99.28

99.28, 0.72

77.28, 72

72, 77.28

Part - B

Generic 2 - Answer All Question

How does thermonuclear fusion reaction occurs?

Give the mass number and atomic number of elements on the right-hand side of the decay process \(^{ 220 }_{ 86 }\)Rn \(\rightarrow\) Po + He.

What is nuclear chain reaction?

In alpha decay, why the unstable nucleus emits \(_{ 2 }^{ 4 }{ He }\) nucleus? Why it does not emit four separate nucleons?

What is meant by fissile material? Give an example for fissile material?
Why neutrons in the nucleus are stable?

Classify the neutrons according to their kinetic energy.

Comment on the statement - "A nucleus contains to electrons and can eject them"

Define atomic mass unit u.

What is mean life of nucleus? Give the expression.

Give the physical meaning of binding energy per nucleon.

A fusion reaction is more energetic than a fission reaction. Why?

Part - C

Generic 3 - Answer All Question

Define atomic mass unit. Find its energy equivalent in MeV.

What is the diameter of H₂ atom?

What does a neutron moderator do?

Show that the decay rate 'R' of a sample of a radionuclide is related to the number of radioactive nuclei 'N' at the same instant by the expression R = \(\lambda\)N.

If the total number of neutrons and protons in a nuclear reaction is conserved how than is the energy absorbed or evolved in the reaction? Explain.

With respect to power generation, what are the relative advantages and disadvantages of fusion type and Fission type reactors?

Write the properties of neutrino?

Energy released per fission of a nucleus is of the order of 200 MeV whereas that per fusion is of the order of 10 MeV. But a fusion bomb (Hydrogen bomb) is said to be more powerful than a fission bomb. Explain why?

What are radioactive elements? What are the factors that affect radio activity?

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12th Physics weekly Test - 3 ( Atomic and Nuclear physics )

St. Britto Hr. Sec. School - Madurai

12th Physics weekly Test - 3 ( Atomic and Nuclear physics )-Aug 2020

Part - A

Multiple Choice Question - Answer All Question

The charge of cathode rays is

Wave number is defined as the number of wave

Controlled chain reaction is seen in ______

Positively charged radioactive rays are called _____ rays.

The first nuclear reactor was built at _________

In a discharge tube, the source of positive rays is

In J.J. Thomson e/m experiment, a beam of electron is replaced by that of muons (particle with same charge as that of electrons but mass 208 times that of electrons). No deflection condition is achieved only if

For first order X-ray diffraction, the wavelength in of the X-ray is equal to the lattice spacing at a glancing angle is

In the nuclear reaction 4Be9 + X \(\rightarrow\) 6C12 + 0n1 X stands for

Radioactive materials are kept in thick-walled ______ containers.

The ground state energy of hydrogen atom is 13.6 eV. The energy needed to ionize H2 atom from its second excited state.

Curie is a unit of

The direction of deflection shows that cathode rays are ___ in charge.

Which of the following is not a moderactor?

An oil drop carrying a charge q has a mass m kg. It is falling freely in air with terminal speed v. The electric field required to make the drop move upwards with the same speed is

Atomic number of H-Iike atom with ionization potential 122.4 V for n = 1 is

J.J. Thomson's experiment demonstrated that

Assertion : Electrons in the atom are held due to coulomb forces. Reason : The atom is stable only because the centripetal force due to coulomb's law is balanced by the centrifugal force.

\(\alpha\)-rays consist of \(\alpha\)-particles, which are ___ nuclei.

A system consists of N0 nucleus at t = 0. The number of nuclei remaining after half of a half-life (that is, at time t = \(\frac { 1 }{ 2 } { T }_{ \frac { 1 }{ 2 } }\))

Assertion : Electron capture occurs more often than positron emission in heavy elements.. Reason : Heavy elements exhibit radio activity.

A radiation of a particular wavelength is called a ____.

Natural uranium consists of _________ % of U235 and _________ % of U238.

Part - B

Generic 2 - Answer All Question

How does thermonuclear fusion reaction occurs?

Give the mass number and atomic number of elements on the right-hand side of the decay process \(^{ 220 }_{ 86 }\)Rn \(\rightarrow\) Po + He.

What is nuclear chain reaction?

In alpha decay, why the unstable nucleus emits \(_{ 2 }^{ 4 }{ He }\) nucleus? Why it does not emit four separate nucleons?

What is meant by fissile material? Give an example for fissile material?

Why neutrons in the nucleus are stable?

Classify the neutrons according to their kinetic energy.

Comment on the statement - "A nucleus contains to electrons and can eject them"

Define atomic mass unit u.

What is mean life of nucleus? Give the expression.

Give the physical meaning of binding energy per nucleon.

A fusion reaction is more energetic than a fission reaction. Why?

Part - C

Generic 3 - Answer All Question

Define atomic mass unit. Find its energy equivalent in MeV.

What is the diameter of H2 atom?

What does a neutron moderator do?

Show that the decay rate 'R' of a sample of a radionuclide is related to the number of radioactive nuclei 'N' at the same instant by the expression R = \(\lambda\)N.

If the total number of neutrons and protons in a nuclear reaction is conserved how than is the energy absorbed or evolved in the reaction? Explain.

With respect to power generation, what are the relative advantages and disadvantages of fusion type and Fission type reactors?

Write the properties of neutrino?

Energy released per fission of a nucleus is of the order of 200 MeV whereas that per fusion is of the order of 10 MeV. But a fusion bomb (Hydrogen bomb) is said to be more powerful than a fission bomb. Explain why?

What are radioactive elements? What are the factors that affect radio activity?

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In the nuclear reaction ₄Be⁹ + X \(\rightarrow\) ₆C¹² + ₀n¹ X stands for

The ground state energy of hydrogen atom is 13.6 eV. The energy needed to ionize H₂ atom from its second excited state.

Assertion : Electrons in the atom are held due to coulomb forces.
Reason : The atom is stable only because the centripetal force due to coulomb's law is balanced by the centrifugal force.

A system consists of N₀ nucleus at t = 0. The number of nuclei remaining after half of a half-life (that is, at time t = \(\frac { 1 }{ 2 } { T }_{ \frac { 1 }{ 2 } }\))

Assertion : Electron capture occurs more often than positron emission in heavy elements..
Reason : Heavy elements exhibit radio activity.

Natural uranium consists of _ % of U²³⁵ and _ % of U²³⁸.

What is the diameter of H₂ atom?