$A$ neutrino is a particle,which is

$STATEMENT-1$: The plot of atomic number ($y$-axis) versus number of neutrons ($x$-axis) for stable nuclei shows a curvature towards the $x$-axis from the line of $45^{\circ}$ slope as the atomic number is increased.
$STATEMENT-2$: Proton-proton electrostatic repulsions begin to overcome attractive nuclear forces in heavier nuclides,requiring more neutrons to maintain stability.

$A$ heavy nucleus at rest breaks into two fragments which fly off with velocities in the ratio $3: 1$. The ratio of radii of the fragments is

When a $U^{238}$ nucleus,initially at rest,decays by emitting an alpha particle with speed $u$,what will be the recoil velocity of the residual nucleus?

The particle that possesses half-integral spin is:

Define isotopes,isobars,and isotones.