Nuclear Physics MCQ Level – 2 - IIT JAM MCQ

Mass number reduces by 4 and number of protons by 1
option 1 says

∴  The first stage would be a β^- decay and the second would be α emission.

The correct answer is:  β^- emission with an anti neutrino  → α  emission

The correct answer is: random process

The correct answer is: to provide more attractive strong nuclear force to balance the repulsive electromagnetic force.

The correct answer is: Iron

The binding energy is the energy that keeps a nucleus together and makes its mass slightly different than its constituent particles.

If its masses were exactly the same as its constituent particles, its B.E would be 0 and it would be unstable.

Now, since the nucleus fissions into 2 equal fragmens.

∴  Each would have a mass number half of that of parent nucleus.

i.e.  A = 119 for each daughter nucleus. The difference in the Binding energies of the product and parent nucleus would be the K.E of the products.

If we assume that the daughter nucleus (each with A = 119 or A ~ 120) has a B.E of x per nucleon.

∴    –7.6 × 238 + x × 119 + x × 119 = 200 MeV
(–7.6 + x) 238 = 200
–7.6 + x = 0.83
x = 7.6 + 0.83
x = 8.43
~ 8.5 MeV/nucleus

The correct answer is: Nuclei near A = 120 must be bound by about 8.5 MeV/nucleon.

Use the process of elimination.

An  α  decay would change the atomic number from 7. So it cannot be option 1. A beta decay requires 2 particles to be emitted e^– / e⁺ and r / r^– option 2 and 3 don’t satisfy this. This leaves us with the 4th option.

The correct answer is: Electron capture by the nucleus with emission of a neutrino.

Since the Nucleus and e^–  have the same spin.

 

Because mass of nucleus >> mass of e^–

The correct answer is: less than 1, because the nucleus has a mass much larger than that of the electron

Since the U nucleus decays at rest.

∴  The products have equal and opposite value of momenta.

The product with greater mass will have lower K.E.

The correct answer is: The Helium nucleus has more kinetic energy than the Thorium nucleus.

The reactions leading to production of energy in the sun are

i.e. 4 Hydrogen atoms and 1 Helium atom.
The correct answer is: 4 Hydrogen atoms and 1 Helium atom.

Since the internal conversion leaves the atom in the excited state (and not the nucleus).

∴  option 2 seems most probable

The correct answer is: atom emits one or several X-rays