The atomic mass of thorium ²³⁴₉₀Th is 234.04359 u, while that of protactinium .²³⁴₉₀Pa is 234.04330 u. Find the energy released when β⁻ decay changes ²³⁴₉₀Th into ²³⁴₉₁Pa.
(A) 1 MeV
(B) 0.5 MeV
(C) 027 MeV
(D) 0.11 Mev