For a radioactive substance with half life t1/2 and initial number of nuclei N0. The number the nuclei decayed in 3 half lives is :
Number of nuclei remaining after
n half lives is
The correct answer is:
A singly charged positive ion is accelerated through a potential difference of 1000V in a mass spectrograph. It then passes through a uniform magnetic field B = 1500 Gauss and then deflected into a circular path of radius 0.122 m.
Select the correct statements
= 1.09 × 105 m/s
The correct answers are: The speed of the ion is 1.09 × 105 m/s, The mass of the ion is 2.68 × 10–26 kg
A singly charged positive ion is accelerated through a potential difference of 1000V in a mass spectrograph. It then passes through a uniform magnetic field B = 1500 Gauss and then deflected into a circular path of radius 0.122 m. The mass number of the ion is :
Mass No. = No. of p + No. of neutron
= 2.75 × 102
A = 275
The correct answer is: 275
Choose the correct option for mirror nuclei
Mirror nuclei have same A but the number of neutrons & protons are reversed.
There is a slight difference in the masses of a proton & neutron. This apart from the different coulomb force in mirror nuclei result in the difference in their masses.
The correct answers are: Nuclei with same mass number but the number of neutrons and protons reversed are called mirror nuclei, The mirror nuclei have different masses, The difference in masses is due to the difference in the proton & neutron masses & difference in the coulomb energy.
1 mg of a radioactive material with half life 1600 years is kept for 2000 years. Choose the correct option.
mass remaining after 2000 years is
mass decayed = 0.58 mg
The correct answers are: 0.42 mg material was left after 2000 years, 0.58 mg material decayed in 2000 years
What are the reasons leading to the discovery of a neutrino in the case of a Beta decay
The correct answers are: Continuous βray spectrum instead of a discrete spectrum as would have been the case had there only been an electron emitted, Most electrons were emitted with energy much less than maximum kinetic energy., Non conservation of angular momentum, Non conservation of linear momentum
Nuclear force is
The correct answers are: spin dependent, charge independent, has repulsive core, same between two proton and two neutron
From the Binding energy per nucleon curve, one can deduce that
Nuclei with smaller A fuse to form a nucleus of higher A which has more B.E./nucleon compared to the reactants. Nuclei with higher A(~200) fission into nuclei of smaller A which have higher B.E./nuclei (thus they are more stable).
The correct answers are: Nuclei with lower mass number tend to undergo fusion, Nuclei with larger mass number tend to undergo nuclear fission
Which of the following is true about
α particle emission
has a lower mass number & from the B.E/nucleon v/s A plot, it can be concluded that will have a greater B.E./nucleon as compared to
∴ it would be more stable
∴ α decay is preferred
The correct answers are: 238Pu prefers to decay by emitting an α particle., Emitting an α particle results in a nucleus having greater binding energy per nucleon.
Which of the following is true regarding the beam energies required to probe the inside of nucleus
For an electron beam
~0.22 × 1010
= 2.2 × 109 eV
= 2.2 GeV
For proton beams,
= 8.5 × 106 eV
= 8.5 MeV
The correct answers are: The energy of a proton beam to probe the inside of a nucleus is of order MeV., The energy of an electron beam to probe the inside of a nucleus is of the order of GeV.