Question

${}^{234}U$ has $92$ protons and $234$ nucleons total in its nucleus. It decays by emitting an alpha particle. After the decay it becomes.

• A. ${}^{232}U$
• B. ${}^{232}Pa$
• C. ${}^{230}Th$
• D. ${}^{230}Ra$

Answer 1

The correct option is C ${}^{230}Th$

${}_{92}^{234}U\stackrel{a}{\to }{}_{90}^{230}Th+\alpha$
The mass number of thorium is $230$ and its atomic number, Z is $90$.
The mass number of radium is $226$ and it atomic number is $88$. As it is given ${}^{230}Ra$, students can make a mistake. Also the value of Z is not given. As at one instant, only one $\alpha$ particle can be emitted, unless it is given two successive emission of $\alpha$ particle, Ra cannot be obtained.