Question

The radioactive nuclide `._(90)^(234) Th` shows two successive `beta-` decay followed by one `alpha-` decay. The atomic number and mass number respectively of the resulting atom is:
A. `90` and `230`
B. `92` and `230`
C. `92` and `234`
D. `94` and `230`

Answer 1

Correct Answer - `(a)`
`._(90)^(234) Th rarr ._(90)^(230)Th + ._(2)He^(4) + 2 ._(-1)e^(0)`