The product from the alpha decay of 235U92 is 235Np93 239Pu94 231Th90 233Ra80 236U92

Question

The product from the alpha decay of 235U92 is

235Np93

239Pu94

231Th90

233Ra80

236U92

Answer 1

Alpha decay means the loss of two protons and two neutrons. This is essentially a helium atom. So if you are losing 4 nuclear particles then your atomic mass should go down by four. Also, if you are losing 2 protons your atomic number should go down by two. So you start with:

235 U 92

Lose 4 particles including 2 protons:

(235 - 4) U (92 - 2)

Will not be Uranium anymore it will be Thorium I believe based on the new atomic number of 90:

231 Th 90

This should be your answer