Nuclear Force

Q.

Define binding energy per nucleon.

Q. Which of the following is incorrect about nuclear force?

1. Nuclear force is always attractive
2. Neutron & protons are bound in nuclear by short-range strong force
3. Nuclear force is stronger than coulombic force
4. Nuclear force does not distinguish between neutron & proton

Q. The energy required to iononise a hydrogen like ion in its ground state is $9$ Rydbergs. What is the wavelength of the radiation emitted, when the electron in this ion jumps from the second excited state, to the ground state?

1. $24.2\text{nm}$
2. $\text{11.4 nm}$
3. $\text{35.8 nm}$
4. $\text{8.6 nm}$

Q. A hydrogen atom, initially in the ground state, is excited by absorbing a photon of wavelength $980\mathring{\text{A}}$. The radius of the atom in the excited state, in terms of Bohr radius $a_0$, will be: $(hc=12500\text{eV}\mathring{\text{A}})$

1. $25a_0$
2. $9a_0$
3. $16a_0$
4. $4a_0$

Q. The de broglie wavelength of neutrons in thermal equlibrium at temperature $T$ is

1. $\frac{0.308}{\sqrt{T}}\stackrel{0}{A}$
2. $\frac{0.0308}{\sqrt{T}}\stackrel{0}{A}$
3. $\frac{30.8}{\sqrt{T}}\stackrel{0}{A}$
4. $\frac{3.08}{\sqrt{T}}\stackrel{0}{A}$

Q. Which force is responsible for radioactive decay of nucleus?

1. Strong nuclear force
2. Weak nuclear force
3. Gravitational force
4. Electromagnetic force

Q. In a hydrogen atom, the electron makes the transition from an energy level with quantum number $n$ to another with quantum number $(n-1)$. If $n>>1$, the frequency of radiation emitted is proportional to

1. $\frac{1}{n}$
2. $\frac{1}{n^2}$
3. $\frac{1}{n^{3/2}}$
4. $\frac{1}{n^3}$

Q. A free electron of $2.6\text{eV}$ energy collides with a $H^{+}$ ion. This results in the formation of a hydrogen atom in the first excited state and a photon is released. Find the frequency of the emitted photon. $(h=6.6\times {10}^{-34}\text{Js})$

1. $1.45\times {10}^{16}\text{MHz}$
2. $0.19\times {10}^{15}\text{MHz}$
3. $9.0\times {10}^{27}\text{MHz}$
4. $1.45\times {10}^9\text{MHz}$

Q. In a phtoelectric experiment, ultraviolet light of wavelength $280\text{nm}$ is used with lithium cathode, having work function $\Phi =25\text{eV}$. If the wavelength incident light is switched to $400\text{nm}$, find out the change in the stopping potential.
$(h=6.63\times {10}^{-34}\text{Js},c=3\times {10}^8{\text{ms}}^{-1}$)

1. $0.6\text{V}$
2. $1.1\text{V}$
3. $1.9\text{V}$
4. $1.3\text{V}$

Q. The $k_{\alpha }$ $X$-ray of molybdenum has wavelength $0.071\text{nm}$. If the energy of a molybdenum atoms with a $k$ electron knocked out is $27.5\text{keV}$, the energy of this atom when an $L$ electron is knocked out will be
$\text{(in keV)}$. (Round off to the nearest integer)
$[h=4.14\times {10}^{-15}\text{eVs},c=3\times {10}^8{\text{ms}}^{-1}]$

Q. The photon radiated from hydrogen corresponding to $2^{nd}$ line of Lyman series is absorbed by a hydrogen like atom $X$ in $2^{nd}$ excited state. As a result, the hydrogen like atom ${}^{\prime }{X}^{\prime }$ makes a transition to $n^{th}$ orbit. Then

1. $X=H{e}^{+}$, $n=4$
2. $X=L{i}^{++}$, $n=6$
3. $X=H{e}^{+}$, $n=6$
4. $X=L{i}^{++}$, $n=9$

Q.

(a) Draw the plot of binding energy per nucleon (BE/A) as a function of mass number. Write two important conclusions that can be drawn regarding the nature of nuclear source.
(b) Use this graph to explain the release of energy in both the processes of nuclear fusion and fission.
(c) Write the basic nuclear process of neutron undergoing $\beta$ -decay. Why is the detection of neutrinos found very difficult?

Q. are strong nuclear forces always attractive

Q. Name the force which is responsible for the stability of the nucleus.

Q. The potential energy of the electron in first excited state of hydrogen atom is -

1. $-3.4\text{eV}$
2. $3.4\text{eV}$
3. $6.9\text{eV}$
4. $-6.9\text{eV}$

Q. What is the origin of strong nuclear force?

Q. Arrange these fundamental forces in order of their magnitude, if they act between two protons separated by a distance of $1fm$
$F_G$ is Gravitational force
$F_E$ is Electromagnetic force
$F_N$ is Strong Nuclear Force

1. 
2. 
3. 
4. 

Q.

Out of four basic forces in nature which one is strongest and weakest ? Why?

Q. The kinetic energy of the electron in first excited state of hydrogen atom is -

1. $-2.4\text{eV}$
2. $-3.4\text{eV}$
3. $2.4\text{eV}$
4. $3.4\text{eV}$

Q. Calculate the ionization energy and separation energy for Li2+ ion if electron is in second excited state.

Q. Energy of $24.6\text{eV}$ is required to remove one of the electrons from a neutral helium atom. The energy in $\left(\text{eV}\right)$ required to remove both the electrons from a neutral helium atom is

Q. A free hydrogen atom in ground state is at rest. A neutron of kinetic energy K collides with the hydrogen atom. After collision hydrogen atom emits two photons in succession one of which has energy $2.55eV$. Assume that the hydrogen atom and neutron has same mas.

1. Minimum value of K is $12.75eV$
2. Minimum value of K is $25.5eV$
3. The other photon has energy $10.2eV$
4. Th upper energy level is of excitation energy $12.5eV$

Q. A $100\text{eV}$ electron collides with a stationary helium ion $\left(H{e}^{+}\right)$ in its ground state and excites to a higher level. After the collision the $H{e}^{+}$ ion emits two photons in succession with wavelength $1085{\text{A}}^{\circ }$ and $304{\text{A}}^{\circ }$. Find the principal quantum number of the excited state.
Given $h=6.63\times {10}^{-34}\text{J.s}$

Q. what is difference between weak nuclear force and strong nuclear force they act in atoms nucleas

Q. The Nuclear Potential Energy graph you just saw is because of:

1. The strong nuclear force between two nucleons

2. The electrostatic force between two nucleons

3. The total force between two nucleons
4. None of these

Q. An electron jumps from the $4^{th}$ orbit to the $2^{nd}$ orbit of hydrogen atom. Given Rydberg's constant $R={10}^5{\text{cm}}^{-1}.$
The frequency of the emitted radiation will be (in $\text{Hz}$)

1. $\frac{9}{16}\times {10}^{15}$
2. $\frac{6}{16}\times {10}^{15}$
3. $\frac{3}{6}\times {10}^{15}$
4. $\frac{3}{16}\times {10}^{15}$

Q. Two protons are kept at a separation of 10 nm. Let $F_n$ and $F_e$ be the nuclear force and the electromagnetic force between them.

1. $F_e=F_n$
2. $F_e\gg F_n$
3. $F_e\ll F_n$
4. $F_{e}and{F}_n$ differ only slightly

Q. The wavelength of electromagnetic radiation required to eject the electron from the first orbit to infinity is given by

1. 25.28 Å
2. $\lambda =252.8$Å
3. $0.2528$Å
4. $\lambda =2.528$Å

Q. The energy of the electrons in the first excited state of the hydrogen atom is -

1. $-2.72\text{eV}$
2. $-0.85\text{eV}$
3. $-0.54\text{eV}$
4. $-3.40\text{eV}$

Q. Assertion :Nuclear forces are independent of charges. Reason: Nuclear force is not a short range force.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect