Question

what is the missing particle?

222 86 rn* → ? + 0 0 γ

222 87 fr

222 85 at

222 86 rn

Explanation:

Step1: Analyze mass number

In a nuclear reaction, the mass number is conserved. The mass number of \(^{222}_{86}\text{Rn}^*\) is \(222\), and the mass number of \(\gamma\) (gamma - ray) is \(0\). So the mass number of the missing particle is \(222\) (since \(222=A + 0\), where \(A\) is the mass number of the missing particle).

Step2: Analyze atomic number

The atomic number is also conserved. The atomic number of \(^{222}_{86}\text{Rn}^*\) is \(86\), and the atomic number of \(\gamma\) is \(0\). So the atomic number of the missing particle is \(86\) (since \(86 = Z+0\), where \(Z\) is the atomic number of the missing particle).

Answer:

\(^{222}_{86}\text{Rn}\)