Thorium-232 is an a emitter with 14-billion-year half-life. Radium-228 is a ?^- emitter with 5.75-year half-life. Actinium-228 is a ?^- emitter with 6.13-hour half-life.(a) What?s the third daughter in the thorium-232 decay series?(b) Make a chart similar to Fig. 38.7 showing the first three decays in the thorium series.

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146 Start:* 4.46 x 10°y 145 uranjum-238 144 234Th24.1 d 143 234p6.75 h 142 141 2.45x 10'y 140 139 7.54x 10ʻy 138 226p Ra I 137 1.6x 10'y 136 3.82 d 135 134 218Po 3.11 min 133 132 214Pb 27 m 214Bi 131 19.9 m a decay 130 214po 129 1.6x 10 s _210p B decay 128 22.3 y 210Bi 127 5.01 d 126 210po End point: stable lead-206 125 138 d 124 80 81 82 83 84 85 86 87 88 89 90 91 92 93 Hg TI Pb Bi Po At Rn F Ra Ac Th Pa U Np -- Atomic number, Z Neutron number, A - Z