Tag: physics

Questions Related to physics

In a laboratory experiment on emission from atomic hydrogen in a discharge tube, only a small number of lines are observed where as a lines are present in the hydrogen spectrum of a star. This is because in a laboratory  

nuclear reactions nuclear structure nuclei atomic nuclei physics

  1. The amount of hydrogen taken is much smaller than that present in the star

  2. The temperature of hydrogen is much smaller than that of the star

  3. The pressure of hydrogen is much smaller than that of the star

  4. The gravitational pull is much larger than that in the star

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Correct Option: C

Ionization energy of $Li$(Lithium) atom in ground state in $5.4 eV$. Binding energy of an electron in $Li^+$ ion in ground state is $75.6 eV$. Energy required to remove all three electrons of Lithium (Li) atom is:-

nuclear reactions nuclear structure nuclei atomic nuclei physics

  1. $203.4 \ eV$

  2. $135.4 \ eV$

  3. $81.0 \ eV$

  4. $156.6 \ eV$

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Correct Option: D

In a hypothetical star,two carbon nuclei fuse to form magnesium.The reaction is:(take :$1amu=931MeV/c^2)$
$^{12}C+^{12}C\rightarrow ^{24}Mg$
The energy released per carbon nuclei is: (Mass of $^{24}Mg=23.985amu)$

nuclear reactions nuclear structure nuclei atomic nuclei physics

  1. $13.965 MeV$

  2. $11.12 MeV$

  3. $6.982 MeV$

  4. $10.12 MeV$

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Correct Option: A
Explanation:

$^{12}C+^{12}C\rightarrow ^{24}Mg$
mass of $^{12}C=12.0642 amu$
Total input mass $m _1=2\times 12.0642$
$=24.1284$ amu
Mass of $^{24}Mg$=output mass
$=m _0=23.955$
mass loss $=m _1-m _o$
$Am=24.1284-23.985$
$=0.1434 amu$
Energy released $=0.1434\times 931 Mev$
$=13.965 Mev$

One milligram of matter converted into energy will give

nuclear reactions nuclear structure nuclei atomic nuclei physics

  1. $9$ J

  2. $9 \times 10^{13}$ J

  3. $9 \times 10^5 $ J

  4. $9 \times ^{10}$ J

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Correct Option: D

One mole of radium has an activity of 1/3.7 killo curie. Its decay constant will be 

nuclear reactions nuclear structure nuclei atomic nuclei physics

  1. $\frac{1}{6}\times -10s^{-1}$

  2. $ 10^{-10}s^{-1}$

  3. $ 10^{-11}s^{-1}$

  4. $ 10^{-8}s^{-1}$

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Correct Option: C
Explanation:

Number of mole of radium, $n=1$

The number of nuclei of radium, $N={{N} _{a}}=avagdaro\,\,number=6.023\times {{10}^{23}}$

Activity, $A=\lambda N$

$ \because 1\,\,curie=3.7\times {{10}^{10}}\,decay/\sec  $

$ \dfrac{1}{3.7}\,kilocurie=0.27\,kilocurie=9.99\times {{10}^{12}}\,dacay/\sec  $

So, $\lambda =\dfrac{A}{N}=\dfrac{9.99\times {{10}^{12}}}{6.023\times {{10}^{23}}}=1.65\times {{10}^{-11}}\,$

In each fission energy of $200\ MeV$ is released. How many acts of fission must occur per second to produce a power of $1\ kw$?

nuclear reactions nuclear structure nuclei atomic nuclei physics

  1. $3.1\times 10^{13}$

  2. $1.3\times 10^{16}$

  3. $1.4\times 10^{16}$

  4. $2.3\times 10^{15}$

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Correct Option: C

The binding energy of  $ _ { 17 } \mathrm { CI } ^ { 35 }$  nucleus is  $298\ \mathrm { MeV }.$  Find its atomic mass. The mass of hydrogen atom  $({ _{ 1 }{ H } }^{ 1 })$  is  $1.008143\  \mathrm { amu }$  and that of a neutron is  $1.008986\  \mathrm { amu }.$  Given  $1\  \mathrm { amu } = 931\  \mathrm { MeV }.$

nuclear reactions nuclear structure nuclei atomic nuclei physics

  1. $148$

  2. $298$

  3. $340$

  4. $348$

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Correct Option: D

In a working nuclear react, cadmium rods (control rods) are used to:-

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  1. Speed up neutrons

  2. Slow down neutrons

  3. Absorb some neutrons

  4. Absorb all neutrons

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Correct Option: C

In the nuclear reaction ; $ _{92}U^{238}\rightarrow _{z}Th^{A}+ _{2}He^{4}$ the values of A and Z are: 

nuclear reactions nuclear structure nuclei atomic nuclei physics

  1. A=230,Z=8

  2. A=234,Z=90

  3. A=228, Z=94

  4. A=232, Z=

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Correct Option: B

Out side a nucleus 

nuclear reactions nuclear structure nuclei atomic nuclei physics

  1. Neutron is stable

  2. Proton and neuron both are stable

  3. Neutrons is unstable

  4. Neither neutrons nor proton is stable

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Correct Option: C