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# An element '$\mathit{X}$' decays first by positron emission and then two $\alpha$ - particles are emitted in successive radioactive decay. If the product nucleus has mass number 227and atomic number 89 the mass number and atomic number of element '$\mathit{X}$' are:

$\begin {array} {1 1} (a)\;(273,93) & \quad (b)\;(235,94) \\ (c)\;(238,93) & \quad (d)\;(237,92) \end {array}$

(b) (235,94)