Question

In the nuclear reaction $\begin{smallmatrix}197\\ 80\end{smallmatrix}X \rightarrow \begin{smallmatrix}197\\ 79\end{smallmatrix}Y + Z + v$, the particle Z is ________.

• A. $\alpha$ particle
• B. $\beta^{+}$ particle
• C. $\beta^{-}$ particle
• D. proton
• E. neutron

Hint:

$\beta^{+}$ decay: Atomic number decreases by 1; $\beta^{-}$ decay: Atomic number increases by 1.

Answer 1

The Correct Option is B

Step 1: Concept
Balance the atomic number (Z) and mass number (A) on both sides of the reaction.

Step 2: Meaning
Mass number remains 197 $\rightarrow$ 197 ($A=0$ for particle Z).

Step 3: Analysis
Atomic number goes from 80 to 79. For the total to remain 80, particle Z must have a charge of +1.

Step 4: Conclusion
A particle with 0 mass and +1 charge is a positron, also known as a $\beta^{+}$ particle. Final Answer: (B)