51. (a) For the first reaction
Q1 = (mRa - mPb - mC)c2
= (223.01850 u - 208.98107 u - 14.00324 u)(931.5MeV/u)
= 31.8 MeV,
and for the second one
Q2 = (mRa - mRn - mHe)c2
= (223.01850 u - 219.00948 u - 4.00260 u)(931.5MeV/u)
= 5.98 MeV .
(b) From U " q1q2/r, we get

qPb qC (82e)(6.0e)
U1 H" U2 =(30.0MeV) =86 MeV.
qRn qHe (86e)(2.0e)