Radon $({R_n})$ decays into Polonium (${P_0}$) by emitting an $\alpha - $ particle with half-life of $4\, days$. A sample contains $6.4 \times {10^{10}}$ atoms of $R_n$. After $12\, days$, the number of atoms of ${R_n}$ left in the sample will be

The half life of a radioactive isotope $X$ is $50$ years. It decays to another element $Y$ which is stable. The two elements $X$ and $Y$ were found to be in the ratio of $1 : 15$ in a sample of a given rock. The age of the rock was estimated to be..........$years$

Ten percent of a radioactive sample has decayed in $1$ day. After $2$ days, the decayed percentage of nuclei will be ...... $\%$

The sun radiates energy in all directions. The average radiations received on the earth surface from the sun is $1.4\;kilowatt/{m^2}$.The average earth- sun distance is $1.5 \times {10^{11}}metres$. The mass lost by the sun per day is($1$ day $= 86400$ seconds)

The half lives of a radioactive substance are $T$ and $2T$. years for $\alpha  - $ emission and $\beta - $ emission respectively. The total de cay constnnt for simultaneous decay of $\alpha$ and $\beta$ adioactive substance is ___

The rate of disintegration was observed to be ${10^{17}}$ disintegrations per sec when its half life period is $1445$ years. The original number of particles are