3. Radioactive decay of nuclei often involves several decays before a stable nucleus is formed. This is called a decay chain. What stable isotope is formed when radon-222 undergoes a decay chain of four alpha decays followed by four beta decays?

Question

(A) tungsten-206
(B) platinum-206
(C) lead-206
(D) tungsten-214
(E) lead-214

4. Which nucleus balances the following nuclear equation for the fission of uranium-23? 235/92 U + 1/0 n -> 90/38 Sr + A/Z X + 2 1/0 n + y

(A) 146/54 Xe
(B) 146/52 Te
(C) 144/52 Te
(D) 144/54 Xe
(E) 142/50 Sn

Any help would be greatly appreciated; I don't understand this AT ALL. Please and thank you!

Answer 1

four alpha means 4*2+) have left

Rn222 is 86X222
so take away 4*mass of alpha, and 4 charge of alpha, you get
78X214, and element 78 is Pt, and weight
then you have 78Pt204, then four beta decays leave the mass as 204, but changes the atomic number to 82
82Pt204