In the Gold foil experiment of Geiger and Marsden, that paved the way for Rutherford's model of an atom, ~ 1.00% of the $\alpha$-particles were found to deflect at angles > ${50}^0$. If one mole of $\alpha$-particles were bombarded on the gold foil, compute the number of $\alpha$-particles that would deflect at angles less than ${50}^0$.

Q. In the geiger-marsden experiment what percentage of the $\alpha$ particles were deflected by an angle more than $1^o$.

Q. Why are the "deflections caused by an aluminum foil less than that of gold foil in an $\alpha$-ray scattering experiment. Can these deflections be changed by changing the kinetic energy of $\alpha$-particles".

Q. Assertion :During Rutherford's gold foil experiment, very few $\alpha$ particles deflected back. Reason: The nucleus present inside the atom is heavy.

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. Deflection back of a few particles by large angle on hitting thin foil of gold in Rutherford's experiment showed that :