On emission of 2 alpha particles, mass number is reduced by 8 and atomic number by 4 . ${}_{z} S^{A} \rightarrow {}_{z-4} Q^{A-8} + 2 {}_2 \mathrm{He}^4$ Now, on emission of 1 beta particle, mass number remains same but atomic number increases by 1 . $z-4 Q^{A-8} \rightarrow Z-3 R^{A-8} + {}_{-1}^0 \beta$ After decay, given element is ${}_{85} \mathrm{R}^{222}$. Therefore $A-8 = 222 \;\; \Rightarrow \;\; A = 230$ (Atomic Mass) $Z-3 = 85^{\circ} \Rightarrow Z = 88$ (Atomic No.)