Rutherford's Model

Q.

Light of two different frequencies whose photons have energies of 1eV and 2.5 eV

respectively successively illuminate a metal of work function 0.5eV.The ratio of maximum speed of emitted electrons is

1. 1:5

2. 1:3

3. 1:2

4. 1:4

Q.

With what velocity should an alpha- particle travel toward the nucleus of a copper atom at a distance of ${10}^{-13}m$ from the nucleus of the copper atom ?

Q.

What do you mean by $1\mathrm{eV}$?

Q. If the energy in the first excited state in hydrogen atomis 23.8 eV then the potential energy and kinetic energ of a hydrogenatom in the ground state can be assumed to be(1) 10 eV(3) 13.6 eV(2) 23.3 eV(4) Zero

Q. What is the angular momentum of an electron in Bohr’s hydrogen atom whose energy is - 0.544 eV.

1. $\frac{5h}{2\pi }$
2. $\frac{7h}{2\pi }$
3. $\frac{h}{\pi }$
4. $\frac{2h}{\pi }$

Q.

An electron and proton enter a magnetic field with equal velocities. Which one of them experiences a greater force?

Q. An electron of a stationary hydrogen atom makes a transition from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be ($m$ is the mass of the electron, $R$ is the Rydberg constant and $h$ is the Planck's constant)

1. $\frac{24hR}{25m}$
2. $\frac{25hR}{24m}$
3. $\frac{25m}{24hR}$
4. $\frac{24m}{25hR}$

Q. The force of attraction between the positively charged nucleus and the electron in a hydrogen atom is given by $F=k\frac{e^2}{r^2}$. Assume that the nucleus is fixed. The electron, initially moving in an orbit of radius $R_1$ jumps into an orbit of smaller radius $R_2.$ The decrease in the total energy of the atom is-

1. $\frac{k{e}^2}{2}(\frac{1}{R_1}+\frac{1}{R_2})$
2. $\frac{k{e}^2}{2}(\frac{R_1}{R_2^2}-\frac{R_2}{R_1^2})$
3. $\frac{k{e}^2}{2}(\frac{1}{R_2}-\frac{1}{R_1})$
4. $\frac{k{e}^2}{2}(\frac{1}{R_1^2}-\frac{1}{R_2^2})$

Q. When a hydrogen atom is raised from the ground state to third state (1) Both kinetie energy and potential energy increases(2), Both kinetic energy and potential energy decreases (3) Potential energy increases and kinetic energy decreases (4) Potential energy decreases and kineltic energy increases

Q. The energy levels of a hypothetical one electron atom is given by $E_n=\frac{-18.0}{n^2}eV$ where
n = 1, 2, 3, .....
Find the wavelength which will not be emitted when these atoms in the ground state are bombarded by electrons that have been accelerated through a potential difference of 16.2 V.

1. $4950\stackrel{\circ }{A}$
2. $773\stackrel{\circ }{A}$
3. $917\stackrel{\circ }{A}$
4. $733\stackrel{\circ }{A}$

Q. Choose the correct alternative from the clues given at the end of the each statement: (a) The size of the atom in Thomson’s model is .......... the atomic size in Rutherford’s model. (much greater than/no different from/much less than.) (b) In the ground state of .......... electrons are in stable equilibrium, while in .......... electrons always experience a net force. (Thomson’s model/ Rutherford’s model.) (c) A classical atom based on .......... is doomed to collapse.(Thomson’s model/ Rutherford’s model.) (d) An atom has a nearly continuous mass distribution in a ..........but has a highly non-uniform mass distribution in ..........(Thomson’s model/ Rutherford’s model.) (e) The positively charged part of the atom possesses most of the mass in .......... (Rutherford’s model/both the models.)

Q. In which of the following processes, the number of protons in the nucleus increase?

1. $\alpha -\text{decay}$
2. ${\beta }^{-}-\text{decay}$
3. ${\beta }^{+}-\text{decay}$
4. $\gamma -\text{decay}$

Q. The wavelength of the light emitted, as an electron jumps from second orbit to first orbit in a hydrogen atom is,

1. $1.225\times {10}^{-7}\text{m}$
2. $1.225\times {10}^{-5}\text{m}$
3. $1.225\times {10}^{-4}\text{m}$
4. $1.225\times {10}^{-3}\text{m}$

Q.

In 1911, the physicist Ernest Rutherford discovered that atoms have a tiny, dense nucleus by shooting positively charged particles at a very thin gold foil. A key physical property which led Rutherford to use gold was

1. Electrically conducting

2. Highly malleable

3. Shiny

4. Non-reactive

Q. Magnetic field does not cause deflection in

1. Alpha rays
2. Beta-plus rays
3. Gamma rays
4. Beta-minus rays

Q. It is observed that some of the spectral lines in hydrogen spectrum have wavelengths almost equal to those of the spectral lines in $H{e}^{+}$ ion, Out of the following the transitions in $H{e}^{+}$ that will make this possible is

1. $n=3\text{to}n=1$
2. $n=6\text{to}n=4$
3. $n=5\text{to}n=3$
4. $n=3\text{to}n=2$

Q. The wavelength of a photon is $1.4A^{\circ }$. It collides with an electron. Its wavelength after the collision is $2.0A^{\circ }$. Calculate the energy of the scattered electron.
Report n if the answer in joule is $n\times {10}^{-16}$
Here plank's constant $h=6.63\times {10}^{-34}{\text{m}}^2\text{kg/s}$

Q. When ${}_{92}{U}^{237}$ nucleus is converted into ${}_{83}B{i}^{209},x$ and $y$ are the number of $\alpha$ and $\beta$ particles emitted respectively then the value of $x$ and $y$, are respectively

1. $5,7$
2. $7,6$
3. $6,7$
4. $7,5$

Q. Answer the following questions, which help you understand the difference between Thomson’s model and Rutherford’s model better. (a) Is the average angle of deflection of α-particles by a thin gold foil predicted by Thomson’s model much less, about the same, or much greater than that predicted by Rutherford’s model? (b) Is the probability of backward scattering (i.e., scattering of α-particles at angles greater than 90°) predicted by Thomson’s model much less, about the same, or much greater than that predicted by Rutherford’s model? (c) Keeping other factors fixed, it is found experimentally that for small thickness t, the number of α-particles scattered at moderate angles is proportional to t. What clue does this linear dependence on t provide? (d) In which model is it completely wrong to ignore multiple scattering for the calculation of average angle of scattering of α-particles by a thin foil?

Q. The surface area $\left(X\right)$ of a nucleus varies with mass number $\left(A\right)$ as:

1. $X\propto A^3$
2. $X\propto A^2$
3. $X\propto A^{\frac{1}{3}}$
4. $X\propto A^{\frac{2}{3}}$

Q. If potential energy is taken to be zero for an electron in ground state of hydrogen atom, then calculate its total mechanical energy in the 1st excited state.

Q. Magnetic field does not cause deflection in
(a) α-rays
(b) beta-plus rays
(c) beta-minus rays
(d) gamma rays

Q.

Why is it said that inside a liquid, the attraction due to surrounding molecules results in a negative potential energy for a molecule ?

Q. A uniform magnetic field with a slit system is shown in the figure. This setup is to be used as a momentum fliter for high energy charged particles. With a field of $B\text{T}$, it is found that the filter transmits $\alpha$-particle each of energy <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> $5.3\text{MeV}$. The magnetic field is increased to $2.3B\text{T}$ and deutrons are passed into the filter. what is the energy of each deutron transmitted by filter?

1. $4.5\text{MeV}$
2. $8.6\text{MeV}$
3. $14.02\text{MeV}$
4. $18.04\text{MeV}$

Q. A decay is given by ${}_{15}^{32}P{⟶}_{16}^{32}S+A+B$, then A & B are

1. ${\beta }^{-1},\overrightarrow{v}$ (antineutrino)
2. ${\beta }^{-1}$, gamma particle
3. $\alpha ,\overrightarrow{v}$ (antineutrino)
4. ${\beta }^{-1},v$ (neutrino)

Q.

Give the reasons and differences between the Thomsons model of atom and the present model of atom.

Q. Using Rutherford model of the atom, derive the expression for the total enrgy of the electron in hydrogen atom. What is the significance of total negative energy possessed by the electron?

Q.

Describe J.J Thomsons atomic model.

Q. In Rutherford's model if the electron of Hydrogen atom is going with a velocity v around the nucleus, then find the magnitude of potential energy of the electron.

1. 
2. None of these
3. 
4. 

Q. Express the velocity of an electron in the n-th orbit of the hydrogen atom, in terms of the principal quantum number n itself.

1. 
2. 
3. 
4.