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 \[1.5\times {{10}^{7}}m/s,\] what is the recoil speed of the resultant radon nucleus? Assume the momentum of \[\gamma \]ray is negligible compared to that of \[\alpha \]particle.

Radium \[^{226}Ra,\] spontaneously decays to radon with the emission o

1.	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 \[1.5\times {{10}^{7}}m/s,\] what is the recoil speed of the resultant radon nucleus? Assume the momentum of \[\gamma \]ray is negligible compared to that of \[\alpha \]particle.
A.	\[1.6\times {{10}^{4}}m/s\]
B.	\[2.7\times {{10}^{5}}m/s\]
C.	\[1.3\times {{10}^{6}}m/s\]
D.	\[2.6\times {{10}^{3}}m/s\]
Answer» C. \[1.3\times {{10}^{6}}m/s\]