Q: In the nuclear reaction _{92}U^{235} → _{82}Pb^{207} , the number of α and β particles lost would be

(A) 8 , 4

(B) 6 , 2

(C) 7 , 4

(D) 4 , 3

Solution: _{92}U^{235} → _{82}Pb^{207} + x (_{2}α^{4}) + y (_{-1}β^{0})

235 = 207 + 4x ⇒ x = 7

92 = 82 + 2x – y or y = 4

Ans: (C)