How many alpha and beta particles are emitted when Uranium ${ }_{92} U ^{238}$ decays to lead ${ }_{82} Pb ^{206}$ ?

An atomic nucleus $_{90}T{h^{232}}$ emits several $\alpha$ and $\beta$ radiations and finally reduces to $_{82}P{b^{208}}$. It must have emitted

Which of the following is in the increasing order for penetrating power

In the nuclear decay given below 

$_z{X^A}{ \to _{z + 1}}{Y^A}{ \to _{z - 1}}{K^{A - 4}}{ \to _{z - 1}}{K^{A - 4}}$

the particles emitted in the sequence are

A nuclear decay is possible if the mass of the parent nucleus exceeds the total mass of the decay particles. If $M(A, Z)$ denotes the mass of a single neutral atom of an element with mass number $A$ and atomic number $Z$, then the minimal condition that the $\beta$ decay $X_Z^A \rightarrow Y_{Z+1}^A+\beta^{-}+\bar{v}_e$ will occur is ( $m_e$ denotes the mass of the $\beta$ particle and the neutrino mass $m_v$ can be neglected)

In gamma ray emission from a nucleus