Question

If uranium (mass number 238 and atomic number 92) emits an $\alpha$ particle, the product has mass number and atomic number:

• A. 236 and 92
• B. 234 and 90
• C. 238 and 90
• D. 236 and 90

Answer 1

The correct option is B 234 and 90

${}^{238}U{\to }_{90}^{234}Th{+}_2^{4}He$

an alpha particle has a mass number and atomic number equal to He.

Thus B is correct