Radioactive Decays: Alpha, Beta, Gamma question from MHT CET 2025 (23 Apr, Shift 2)

Answer: (a)

1. Each $\alpha$: $A \to A-4$, $Z \to Z-2$. Each electron ($\beta^-$): $Z \to Z+1$. Each positron ($\beta^+$): $Z \to Z-1$.
2. Mass number: $242 - 2(4) = 234$ (matches).
3. Atomic number: $P = 92 - 2(2) + 1 - 2 = 87$
4. So the answer is (a) 87.