In the reaction: , X is — Nuclear Chemistry and Radioactivity Chemistry Question

💡 Solution & Explanation

Equating total mass numbers on both sides: $9 + A_X = 10 \implies A_X = 1$. Equating atomic numbers: $4 + Z_X = 5 \implies Z_X = 1$. The particle with $A=1$ and $Z=1$ is a proton (${}_1\text{H}^1$). Therefore, correct answer is A.