The unit for nuclear dose given to a patient is

For the given reaction, the particle $X$ is $_6C^{11} \to _5B^{11} + \beta^+ + X$.

When a nucleus with atomic number $Z$ and mass number $A$ undergoes a radioactive decay process:

Which one of the following cannot emit $\gamma$-radiation and why? $(i)$ Excited nucleus,(ii) Excited electron.

$U^{238}$ decays into $Th^{234}$ by the emission of an $\alpha$-particle. There follows a chain of further radioactive decays,either by $\alpha$-decay or by $\beta$-decay. Eventually,a stable nuclide is reached,and after that,no further radioactive decay is possible. Which of the following stable nuclides is the end product of the $U^{238}$ radioactive decay chain?

In the uranium radioactive series, the initial nucleus ${}^{238}_{92}U$ decays to the final nucleus ${}^{206}_{82}Pb$. In this process, the number of $\alpha$-particles and $\beta$-particles emitted are: