The disintegration constant of radium with a half-life of $1600 \ years$ is:

Half-life period of a radioactive element is $10.6 \ yrs$. How much time will it take in its $99 \ \%$ decomposition?

The half-lives of two radioactive nuclides $A$ and $B$ are $1 \ min$ and $2 \ min$ respectively. Equal weights of $A$ and $B$ are taken separately and allowed to disintegrate for $4 \ min$. What will be the ratio of weights of $A$ and $B$ disintegrated?

$A$ sample is obtained from sea water. $11.9$ $C^{14}$ atoms dissociate from $1 \ g$ of carbon. $15.3$ $C^{14}$ atoms dissociate from a live sample. How many years old is the sample? $(t_{1/2} = 5730 \ \text{years})$

If a substance with a half-life of $3 \ days$ is kept for $12 \ days$,what fraction of the substance remains?

The half-life of $^{14}C$ is about $.........$ $years$.