Tag: nuclei

Questions Related to nuclei

The excitation energy of a hydrogen like ion to first excited state is 40.8 eV. The energy needed to remove the electron from the ion the ground state is

physics nuclei nuclear force the nuclear force nuclear force and binding energy

  1. 54.4 eV

  2. 62.6 eV

  3. 72.6 eV

  4. 58.6 eV.

Show answer
Correct Option: A
Explanation:

For a hydrogen atom like system the energy for $n^{th}  $ level is given by $E _n=\dfrac{-13.6Z^2}{n^2}eV$

So the ground state energy will be $E _1=\dfrac{-13.6Z^2}{1}eV$
and for the state $n=2$ the energy is $E _2=\dfrac{-13.6Z^2}{4}eV$
So the excitation energy foe this state will be $E _2 -E _1=10.2Z^2eV$
as it is given to be $40.8eV$  so $Z^2=4$ or $Z=2$
So the energy in ground state will be $E _1=-54.4eV$
so the inonization energy will be $-(-54.4eV)=54.4eV$

What is the maximum value of binding energy per nucleon ?

physics nuclei nuclear force the nuclear force nuclear force and binding energy

  1. 8 MeV

  2. 8.8 MeV

  3. 7.6 MeV

  4. 1.1 MeV

Show answer
Correct Option: B
Explanation:

Answer is (B)

The Binding energy curve reaches a maximum value of 8.79

Identify the correct statement/statements:
a) At greater distances nuclear forces are negligible
b) Nuclear forces are non central forces
c) Nuclear forces are weakest in nature
d) Nuclear forces are charge dependent forces

physics nuclei nuclear force the nuclear force nuclear force and binding energy

  1. a, b

  2. b, c

  3. c, d

  4. a, d

Show answer
Correct Option: A
Explanation:

Nuclear forces properties :
1) They will act upto nearly one ferms. Beyond that they become negligible.
2) Charge independent : $F _{pp} = F _{pn} = F _{nn}$
3) They do not act along the line joining the centres of the nuclears, so they are non-central forces.
4) Nuclear forces are strong in nature.
So, correct choice is option A.

Let $F _{pp},F _{pn}$ and $F _{nn}$ denote the magnitudes of the nuclear force by a proton on a proton, by a proton on a neutron and by a neutron on a neutron respectively when the separation is less than one Fermi. Then

physics nuclei nuclear force the nuclear force nuclear force and binding energy

  1. $F _{pp}>F _{pn}= F _{nn}$

  2. $F _{pp}=F _{pn}= F _{nn}$

  3. $F _{pp}>F _{pn}> F _{nn}$

  4. $F _{pp}< F _{pn}= F _{nn}$

Show answer
Correct Option: B
Explanation:

At separation less than one fermi,  the nuclear force of attraction is strongly active and Nuclear force is charge independent force.

Hence , $F _{pp} = F _{pn} = F _{nn}$

Among the following, short range, charge independent and spin dependent forces are

physics nuclei nuclear force the nuclear force nuclear force and binding energy

  1. Gravitational forces

  2. Nuclear forces

  3. Electromagnetic forces

  4. Weak forces

Show answer
Correct Option: B
Explanation:

Nuclear force is short range, charge independent and spin independent force.

Among gravitational,electrostatic and nuclear forces,the two attractive forces between two neutrons are

physics nuclei nuclear force the nuclear force nuclear force and binding energy

  1. Electrostatic and nuclear

  2. Electrostatic and gravitational

  3. Gravitational and nuclear

  4. Electrostatic

Show answer
Correct Option: C
Explanation:

Neutrons have no charge on them. So, there is no electrostatic force. But we have gravitational and nuclear forces on two neutrons because neutrons have masses and gravitational force depends on mass.
So, correct choice is option C.

Among the following interactions, the one of least significance in nuclear physics is

physics nuclei nuclear force the nuclear force nuclear force and binding energy

  1. nuclear interaction

  2. gravitational interaction

  3. electrostatic interaction

  4. electromagnetic interaction

Show answer
Correct Option: B
Explanation:

Since, masses of electrons, protons and neutrons are negligible. So, we often neglect gravitational interaction in nuclear physics.

Two protons attract each other when the distance between them is 

physics nuclei nuclear force the nuclear force nuclear force and binding energy

  1. $10^{-18}$m

  2. $10^{-20}$m

  3. $10^{-15}$m

  4. $10^{-22}$m

Show answer
Correct Option: C
Explanation:

Two protons attracts each other when distance between them is less than $10^{-15}m.$

Two protons are kept at a separation of $10$nm. Let $F _{n}$ be the nuclear force and $F _{e}$ be electromagnetic force between them. Then,

physics nuclei nuclear force the nuclear force nuclear force and binding energy

  1. $F _{e}= F _{n}$

  2. $F _{e}>> F _{n}$

  3. $F _{e}<< F _{n}$

  4. $F _{n}= F _{e}$

Show answer
Correct Option: B
Explanation:

At separation greater than fermi, nuclear force is negligible. So, electromagnetic force is much powerful than nuclear force.
So, correct chioce is option B.

Attractive Force exists between two protons inside the Nucleus. This is due to :

physics nuclei nuclear force the nuclear force nuclear force and binding energy

  1. Gravitational Forces

  2. Electro magnetic Forces

  3. Weak Nuclear Forces

  4. Strong Nuclear Forces

Show answer
Correct Option: D
Explanation:

The forces that bind fermions (electron, proton, neutron) together are termed as weak forces. Whereas the forces that bind the constituents of a nucleus are strong nuclear force.