Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei 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  

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In a laboratory discharge tube, the low pressure of hydrogen gas limits the number of collisions and the population of excited states, resulting in fewer observed spectral lines compared to the high-pressure, high-temperature environment of a star.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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:-

  1. $203.4 \ eV$

  2. $135.4 \ eV$

  3. $81.0 \ eV$

  4. $156.6 \ eV$
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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 $^{24}Mg=23.985amu)$

  1. $13.965 MeV$

  2. $11.12 MeV$

  3. $6.982 MeV$

  4. $10.12 MeV$
Reveal answer Fill a bubble to check yourself
A Correct answer
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 $=0.1434\times 931 Mev$
$=13.965 Mev$

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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

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

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

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

  4. $ 10^{-8}s^{-1}$
Reveal answer Fill a bubble to check yourself
C Correct answer
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, $\lambda =\dfrac{A}{N}=\dfrac{9.99\times {{10}^{12}}}{6.023\times {{10}^{23}}}=1.65\times {{10}^{-11}}\,$

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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  $1\  \mathrm { amu } = 931\  \mathrm { MeV }.$

  1. $148$

  2. $298$

  3. $340$

  4. $348$
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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

  1. Speed up neutrons

  2. Slow down neutrons

  3. Absorb some neutrons

  4. Absorb all neutrons
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cadmium rods are used in nuclear reactors to absorb neutrons, which helps control the rate of the fission chain reaction.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

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

  1. A=230,Z=8

  2. A=234,Z=90

  3. A=228, Z=94

  4. A=232, Z=
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In alpha decay, the mass number decreases by 4 and the atomic number decreases by 2. For U-238, A becomes 238 - 4 = 234 and Z becomes 92 - 2 = 90.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

Out side a nucleus 

  1. Neutron is stable

  2. Proton and neuron both are stable

  3. Neutrons is unstable

  4. Neither neutrons nor proton is stable
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Free neutrons outside a nucleus are unstable and decay with a half-life of about 10.2 minutes. Protons, however, are stable particles. The statement 'Neutrons is unstable' (despite the grammatical error) correctly identifies that free neutrons undergo beta decay.