JEE MAIN - Chemistry (2003 - No. 37)
The radionucleide $${}_{90}^{234}Th$$ undergoes two successive $$\beta$$ -decays followed by one $$\alpha$$-decay. The atomic number
and the mass number respectively of the resulting radionucleide are
94 and 230
90 and 230
92 and 230
92 and 234
Uitleg
$${}_{90}^{234}Th\buildrel { - \beta } \over
\longrightarrow {}_{91}^{234}X\buildrel {\, - \beta } \over
\longrightarrow {}_{92}^{234}Th\buildrel { - \alpha } \over
\longrightarrow {}_{90}^{230}Th$$