TG EAMCET 4 May 2025 Shift 2 Paper

Change in mass number

‌=232−208
‌=24

∴ Number of α-particles =‌

24

4

=6
Each beta particle has no change in mass number but increases the atomic number by 1(‌−10e).
Initial atomic number of Thorium (Th)=90.
Atomic number after emitting 6 alpha particles =90−(6×2)=90−12=78
Final atomic number of Lead (Pb)=82.
The increase in atomic number from 78 to 82 must be due to beta decay.
Number of beta particles = Final atomic number - Atomic number after alpha decay

‌=82−78
‌=4