During ~ decay (Beta minus) the emission of anti neutrino particle is supported by which of the following statement (s) ? 

If the nuclear reaction involving ${\beta }^{-}$ decay is 

$n\to p+e^{-1}$, then the spins on two sides are not equal 

as all three neutron, proton and electron have spin of

$\pm \frac{1}{2}$ so to conserve angular momentum (spin) some other particle must be emitted.

Through experiments it has been observed that direction of emitted electron and recoiling nuclei are almost never exactly opposite as required for linear momentum to be conserved. During ~ decay the energies of electron is found to vary continuously from 0 to a maximum value (This maximum value is characteristic of nuclide). To explain this experimental observation also, emission of some other particle is needed which carries away some energy .