The shortest wavelengths of Paschen, Lymen and Balmer series are in the ratio

The radius of a nucleus as measured by electron scattering is $$4.8 \mathrm{~fm}$$. The mass number of nucleus is most likely to be

The ratio of the radii of the nucleus of two element $$\mathrm{X}$$ and $$\mathrm{Y}$$ having the mass numbers 232 and 29 is:

The closest approach of an alpha particle when it make a head on collision with a gold nucleus is $$10 \times 10^{-14} \mathrm{~m}$$, then the kinetic energy of the alpha particle is :