$_6^{12}C$ absorbs an energetic neutron and emits a beta particle. The resulting nucleus is

In medicine,to destroy cancer cells . . . . . . rays are used.

The nucleus $_{90}Th^{228}$ transforms into $_{83}Bi^{212}$. How many $\alpha$-particles and $\beta$-particles are emitted during this process?

Assertion: ${}^{90}Sr$ from the radioactive fallout of a nuclear bomb ends up in the bones of human beings through the milk consumed by them. It causes impairment of the production of red blood cells.
Reason: The energetic $\beta$-particles emitted in the decay of ${}^{90}Sr$ damage the bone marrow.

$A$ nuclear reaction is given by ${}_{Z}X^{A} \to {}_{Z+1}Y^{A} + {}_{-1}e^{0} + \bar{\nu}$,which represents:

$A$ nucleus ${ }_{Z} X^{A}$ emits an $\alpha$-particle with velocity $v$. The recoil speed of the daughter nucleus is