Which of the following interactions is responsible for beta decay?

In $\beta^{-}$ decay, a neutron transforms into a proton within the nucleus according to the equation:
$\text{neutron} \rightarrow \text{proton} + \beta^{-} + x$
In this equation, the particle represented by '$x$' is:

In the given reaction $_Z{X^A} \to _{Z+1}{Y^A} \to _{Z-1}{K^{A-4}} \to _{Z-1}{K^{A-4}}$,radioactive radiations are emitted in the sequence:

$A$ positron is emitted from ${}^{23}Na_{11}$. The ratio of the atomic mass and atomic number of the resulting nuclide is

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

$1$ curie represents