A classical atom based on ____________ is doomed to collapse. (Thomson’s model/ Rutherford’s model.) - Physics

Fill in the Blanks

A classical atom based on ____________ is doomed to collapse.


  • Thomson’s model

  • Rutherford’s model



A classical atom based on Rutherford’s model is doomed to collapse.

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Chapter 12: Atoms - Exercise [Page 435]


NCERT Physics Class 12
Chapter 12 Atoms
Exercise | Q 12.3 (c) | Page 435
NCERT Physics Class 12
Chapter 12 Atoms
Exercise | Q 1.3 | Page 435


With the help of a neat labelled diagram, describe the Geiger- Marsden experiment

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

Thorium 90Th232 is disintegrated into lead 82Pb200. Find the number of α and β particles emitted in disintegration.

The size of the atom in Thomson’s model is ____________ the atomic size in Rutherford’s model.

Suppose you are given a chance to repeat the alpha-particle scattering experiment using a thin sheet of solid hydrogen in place of the gold foil. (Hydrogen is a solid at temperatures below 14 K.) What results do you expect?

Define the distance of closest approach. An α-particle of kinetic energy 'K' is bombarded on a thin gold foil. The distance of the closest approach is 'r'. What will be the distance of closest approach for an α-particle of double the kinetic energy?

Write two important limitations of Rutherford's nuclear model of the atom.

An electron in an atom revolves round the nucleus in an orbit of radius r with frequency v. Write the expression for the magnetic moment of the electron.

In a Geiger-Marsden experiment, calculate the distance of closest approach to the nucleus of Z = 80, when a α-particle of 8Mev energy impinges on it before it comes momentarily to rest and reverses its direction.

How will the distance of closest approach be affected when the kinetic energy of the α-particle is doubles?

The total energy of an electron in the ground state of the hydrogen atom is -13·6 eV. Its total energy, when a hydrogen atom is in the first excited state, is: 

The basic force acting on the alpha particles using Coulomb's law is ______.

The first line of Balmer series (Hα) in the spectrum of hydrogen is obtained when an electron of hydrogen atom goes from ______.

If the radius of second electron orbit in hydrogen atom be r then the radius of the third orbit will be ______.

For 7.7 Mev alpha particles scattering from aluminium (Z = 13), the distance of closest approach in a bead on collision is ______.

Useful data

`1/(4 pi ∈_0) = 8.99 xx 10^9` newton m2C-2; c = 1.60 × 10-19 C; leV = 1.60 × 10-19j.

As compared to 12C atom, 14C atom has ______.

An automobile moves on a road with a speed of 54 km h−1. The radius of its wheels is 0.45 m and the moment of inertia of the wheel about its axis of rotation is 3 kg m2. If the vehicle is brought to rest in l 5s, the magnitude of average torque transmitted by its brakes to the wheel is:

A radioactive nucleus (initial mass number A and atomic number Z) emits 3 α- particles and 2 positrons. The ratio of the number of neutrons to that of protons in the final nucleus will be:

The equation of trajectory of a projectile is given by y = `"x"/sqrt3 - "gx"^2/20`, where x and y are in metres. The maximum range of the projectile is:

The radius of electron's second stationary orbit in Bohr's atom is R. The radius of 3rd orbit will be:-

The ratio of the frequencies of the long wave length its of Lyman Balmer series of hydrogen spectrum is

Which of the following transition in a hydrogen atom emit photon of the highest frequency:

An alpha particle has

In 88 Ra226 nucleus, there are

Would the Bohr formula for the H-atom remain unchanged if proton had a charge (+4/3)e and electron a charge (−3/4)e, where e = 1.6 × 10–19C. Give reasons for your answer.

The electron in a hydrogen atom is typically found at a distance of about 5.3 × 10−11 m from the nucleus which has a diameter of about 1.0 × 10−15 m. Assuming the hydrogen atom to be a sphere of radius 5.3 × 10−11 m, what fraction of its volume is occupied by the nucleus?

The energy levels of a certain atom for first, second and third levels are E, 4E/3 and 2E, respectively. A photon of wavelength λ is emitted for a transition 3 `→` 1. What will be the wavelength of emission for transition 2 `→` 1?

According to Bohr model, magnetic field at centre (at the nucleus) of a hydrogen atom due to motion of electron in the ninth orbit is proportional to:

If λa, λb and λc represent the Kα, Kβ and Lα transition wavelengths in a hydrogen atom, respectively. Then which of the following is correct?

The shortest wavelength of the Brackett series of a hydrogen like atom of atomic number Z is same as the shortest wavelength of the Balmer series of hydrogen atom, then the value of Z is ______.

Choose the correct option from the following options given below:

An alpha nucleus of energy `1/2`mv2 bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to ______.

  1. v2
  2. `1/"m"`
  3. `1/"v"^2`
  4. `1/"Ze"`

In the Rutherford experiment, α-particles are scattered from a nucleus as shown. Out of the four paths, which path is not possible? 


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