Radium `""^(226) Ra` , spontaneously decays to radon with the emission of an `alpha`- particle and a `gamma`-ray . If the speed of the `alpha` particle upon emission from an initially stationary radium nucleus is `1.5 xx 10^(7)` m/s, what is the recoil speed of the resultant radon nucleus ? Assume the momentum of `gamma` ray is negligible compared to that of `alpha` particle

Options

A. `2.0 xx 10^(5)` m/s
B. `2.7 xx 10^(5)` m/s
C. `3.5 xx 10^(5)` m/s
D. `1.5 xx 10^(7)` m/s

Answer

B