A radioactive nucleus decays by two different processes. The half life for the first process is $10\, s$ and that for the second is $100 s$. the effective half life of the nucleus is close to$.....sec$

A sample of radioactive element containing $4 \times 10^{16}$ active nuclei. Half life of element is $10$ days, then number of decayed nuclei after $30$ days is  ........ $\times 10^{16}$ 

A radioactive decay chain starts from $_{93}N{p^{237}}$ and produces $_{90}T{h^{229}}$ by successive emissions. The emitted particles can be

The particle that possesses half integral spin as

For a certain radioactive process the graph between $In\, {R}$ and ${t}\,({sec})$ is obtained as shown in the figure. Then the value of half life for the unknown radioactive material is approximately $....\,{sec}.$

A sample of radioactive element has a mass of $10\, gm$ at an instant $t = 0$.The approximate mass of this element in the sample after two mean lives is ..........$gm$