V K Sally and R Goel Solutions for Chapter: Structure of Atom, Exercise 1: EXERCISE 4A

Who discovered the nucleus within an atom? 

Who discovered neutrons?

Calculate the number of neutrons present in the nucleus of an element X which is represented as ${}_{15}{}^{31}\mathrm{X}$.

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$> 50°$, If one mole of $\alpha$-particles were bombarded on the gold foil, calculate the number of $\alpha$-particles that would deflect at angles less than 50$°$. 

Enlist the conclusions drawn by Rutherford from his $\mathrm{\alpha }$-ray scattering experiment.

In what way was the Rutherford's atomic model different from that of Thomson's atomic model?

The ratio of the radii of hydrogen atom and its nucleus is ~10^5. Assuming the atom and the nucleus to be spherical, 
(i) what will be the ratio of their sizes? 
(ii) If atom is represented by planet earth R_e=6.4×10⁶  m, estimate the size of the nucleus.

Represent the atomic structure of the following elements geometrically, clearly showing
(i) The number of protons, 
(ii) number of neutrons, 
(iii) number of electrons in various shells around the nucleus.

 (i)   ${}_1{}^2\mathrm{H}$,
(ii)   ${}_3{}^7\mathrm{Li}$
(iii)  ${}_{13}{}^{27}\mathrm{Al}$
(iv)  ${}_{20}{}^{40}\mathrm{Ca}$
(v)   ${}_{17}{}^{35}\mathrm{Cl}$