Write the definition and unit of decay constant.
A radio-isotope has a half- life of $5$ years. The fraction of the atoms of this material that would decay in $15$ years will be
A radioactive material has a half life of $10$ days. What fraction of the material would remain after $30$ days
Two radioactive elements $R$ and $S$ disintegrate as
$R \rightarrow P + \alpha; \lambda_R = 4.5 × 10^{-3} \,\, years^{-1}$
$S \rightarrow P + \beta; \lambda_S = 3 × 10^{-3} \,\, years^{-1}$
Starting with number of atoms of $R$ and $S$ in the ratio of $2 : 1,$ this ratio after the lapse of three half lives of $R$ will be :
Ten percent of a radioactive sample has decayed in $1$ day. After $2$ days, the decayed percentage of nuclei will be ...... $\%$
In Fig. $X$ represents time and $Y$ represent activity of a radioactive sample. Then the activity of sample, varies with time according to the curve