(a) What is mean by mass defect ?
(b) What conclusion is drawn from Rutherford’s scattering experiment of `alpha`-particles ?
(a) The difference in mass of a nucleus and its constituent `Δ M` , is called mass defect , and is given by
`DeltaM = [Z.m_p + (A - Z)m_N] - M`
where Z is atomic number, A is mass number, M is mass of the nucleus, `m_p` is mass of a free proton and `m_N` is mass of free neutron.
(b) We can conclude from Rutherford’s scattering experiment of `alpha`-particles, that there is a lot of empty space in an atom.