A radioactive nucleus undergoes a series of decays according to the sequence
`Xoverset(beta)toX_(1)overset(alpha)toX_(2)overset(alpha)toX_(3)`.
f the mass number and atomic number of `X_(3)` are 172 and 69 respectively. what is the mass numberand atomic number of X ?

Explanation

To solve the problem, we need to analyze the decay sequence of the radioactive nucleus step by step.

1. **Understanding the Decay Process**:
- The sequence given is:
- \( X \overset{\beta}{\rightarrow} X_1 \)
- \( X_1 \overset{\alpha}{\rightarrow} X_2 \)
- \( X_2 \overset{\alpha}{\rightarrow} X_3 \)
- Here, \( X \) is the original nucleus, \( X_1 \) is formed after beta decay, \( X_2 \) is formed after the first alpha decay, and \( X_3 \) is formed after the second alpha decay.
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