Alpha-particle scattering and Rutherford's model — practice questions

Question 1 · difficulty L1 · recall

Rutherford's alpha-scattering experiment showed that most alpha particles

• A. passed through the foil with little deflection
• B. were reflected straight back
• C. were absorbed by electrons
• D. lost all charge

Question 2 · difficulty L1 · understanding

Rare large-angle alpha deflections imply that an atom's positive charge is

• A. spread uniformly through the entire atom
• B. concentrated in a very small nucleus
• C. located only on electrons
• D. absent

Question 3 · difficulty L2 · understanding

In an alpha particle scattering experiment distance of closest approach for the $$\alpha$$ particle is $$4.5 \times 10^{-14} \mathrm{~m}$$. If target nucleus has atomic number 80 , then maximum velocity of $$\alpha$$-particle is __________ $$\times 10^5 \mathrm{~m} / \mathrm{s}$$ approximately. ($$\frac{1}{4 \pi \epsilon_0}=9 \times 10^9 \mathrm{SI}$$ unit, mass of $$\alpha$$ particle $$=6.72 \times 10^{-27} \mathrm{~kg}$$)

Question 4 · difficulty L2 · understanding

In Rutherford's alpha-particle scattering experiment, only a few alpha particles rebound back because A. The size of gold nucleus is very small as compared to the size of gold atom. B. Alpha particle and gold nucleus have equal charge. C. The impact parameter is minimum for a few alpha particles. D. A few alpha particles have very high kinetic energy. E. Only a few alpha particles undergo head-on collision with the nuclei. Choose the correct answer from the options given below :

• A. A, B Only
• B. B, E Only
• C. C, D Only
• D. A, C, E Only

Question 5 · difficulty L2 · understanding

Given below are two statements: Statement I : Most of the mass of the atom and all its positive charge are concentrated in a tiny nucleus and the electrons revolve around it, is Rutherford's model. Statement II : An atom is a spherical cloud of positive charges with electrons embedded in it, is a special case of Rutherford's model. In the light of the above statements, choose the most appropriate from the options given below

• A. Both Statement I and Statement II are true
• B. Statement I is true but Statement II is false
• C. Statement I is false but Statement II is true
• D. Both statement I and statement II are false

Question 6 · difficulty L2 · understanding

The energy of $$\mathrm{He}^{+}$$ ion in its first excited state is, (The ground state energy for the Hydrogen atom is $$-13.6 ~\mathrm{eV})$$ :

• A. $$-13.6 ~\mathrm{eV}$$
• B. $$-27.2 ~\mathrm{eV}$$
• C. $$-3.4 ~\mathrm{eV}$$
• D. $$-54.4 ~\mathrm{eV}$$

Question 7 · difficulty L2 · understanding

The waves emitted when a metal target is bombarded with high energy electrons are

• A. Infrared rays
• B. Radio Waves
• C. Microwaves
• D. X-rays

Question 8 · difficulty L2 · understanding

Choose the correct option from the following options given below :

• A. In the ground state of Rutherford's model electrons are in stable equilibrium. While in Thomson's model electrons always experience a net-force.
• B. An atom has a nearly continuous mass distribution in a Rutherford's model but has a highly non-uniform mass distribution in Thomson's model.
• C. A classical atom based on Rutherford's model is doomed to collapse.
• D. The positively charged part of the atom possesses most of the mass in Rutherford's model but not in Thomson's model.

Question 9 · difficulty L2 · understanding

In Rutherford's model, most of the atom's mass is concentrated in

• A. the electron cloud uniformly
• B. empty space
• C. the nucleus
• D. photons between electrons

Question 10 · difficulty L2 · application

The closest approach of a head-on alpha particle to a nucleus is found by equating initial kinetic energy to

• A. gravitational potential only
• B. electron rest energy
• C. magnetic kinetic energy
• D. electrostatic potential energy at closest approach