In the uranium series,the decay constant of the parent nuclide is $\lambda$. What is the decay constant of the stable end product of this series?

The modern treatment method $P.E.T.$ is based on:

The atomic mass number of the element thorium is $232$ and its atomic number is $90$. The end product of this radioactive element is an isotope of lead (atomic mass $208$ and atomic number $82$). The number of alpha and beta particles emitted is:

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.

$A$ nucleus $_n{X^m}$ emits one $\alpha$ particle and two $\beta$ particles. The resulting nucleus is

Which of the following is emitted, when ${ }_{94}^{239} Pu$ decays into ${ }_{92}^{235} U$?