Highly energetic electrons are bombarded on a target of an element containing $30$ neutrons. The ratio of radii of nucleus to that of Helium nucleus is ${14^{1/3}}$. The atomic number of nucleus will be
$25$
$26$
$56$
$30$
The atoms of same element having different masses but same chemical properties, are called
Two nuclei have their mass numbers in the ratio of $1 : 3.$ The ratio of their nuclear densities would be
A heavy nucleus at rest breaks into two fragments which fly off with velocities in the ratio $8 : 1$. The ratio of radii of the fragments is
A nucleus at rest splits into two nuclear parts having same density and the radii in the ratio $1 : 2$ . Their velocities are in ratio ———
Nuclear forces are