Question

In a radioactive decay ${}^{92}{U}_{238}\stackrel{\alpha }{\to }X\stackrel{\alpha }{\to }z{Y}^A$ The values of Z and A:

• A. 92, 236
• B. 88, 230
• C. 90, 130
• D. 88, 234

Answer 1

Answer: (B)

After emission of a-particle, the atomic number of new element is reduced by 2 unit and the atomic mass is reduced by 4 unit. Therefore, the new element after emission of $\alpha -$ particle is ${}_{90}{X}^{234}$ . Again by emission of one more $\alpha -$ particle from ${}_{90}{X}^{234}$ nucleus, new element is ${}_{88}{Y}^{230}$ .