Question

Calculate the number of α- and β-particles emitted when ${}_{92}{U}^{238}$ changes into radioactive ${}_{82}P{b}^{206}.$
(IIT-JEE, 2000)

• A. 3, 4
• B. 6, 8
• C. 4, 3
• D. 8, 6

Answer 1

The correct option is D 8, 6

Let x α- and β-particles be given out during the change. ${}_{92}{U}^{238}\to {}_{82}P{b}^{206}+x{}_{2}H{e}^4+y_{-1}{e}^0$

Equating mass number on both sides,
238 = 206 + 4x + y x 0
∴ x = 8

Equating atomic number on both sides,
92 = 82 + 2x + y(-1) = 82 + 2 x 8 + y(-1)

∴ y = 6

∴ Number of α-particles = 8

Number of β-particles = 6