The decay process illustrated above shows that the lost β -particle to decay to the X by increase its  atomic number ( from 92 to 93) and leaving the mass no. unaffected. There after, x decayed by -α emission to give Y, by decreasing the mass no. by 2 ( from 93 to 91).<br/><br/>Thus , the emission is β and α particles respectively

<p>During the nuclear reaction described by </p><p><table><tbody><tr><td>235</td><td rowspan="2">W →</td><td>235</td><td rowspan="2">X→</td><td>231</td><td rowspan="2">Y</td></tr><tr><td>92</td><td>93</td><td>91</td></tr></tbody></table></p><p>The particles emitted are respectively</p>

Earlier discussion