The radioactive decay of uranium into thorium is expressed by the equation $_{92}^{238}U \to _{90}^{234}Th + X,$ where $X$ is

In the following nuclear reaction,$x$ stands for: $n \rightarrow p + e^{-} + x$

$A$ radioactive nucleus of mass $M$ emits a photon of frequency $v$ and the nucleus recoils. The recoil energy will be

$A$ nucleus of atomic mass $A$ and atomic number $Z$ emits a $\beta^-$ particle. The atomic mass and atomic number of the resulting nucleus are

When $_{90}Th^{238}$ transforms into $_{83}Bi^{222}$,the number of $\alpha$ and $\beta$ particles emitted are:

$A$ radioactive nucleus with $Z$ protons and $N$ neutrons emits an $\alpha$-particle,$2\beta^-$-particles,and $2$ gamma rays. The number of protons and neutrons in the nucleus left after the decay,respectively,are: