$A$ radioactive sample decays to half of its initial concentration in $6.93 \ min$. It further decays half in next $6.93 \ min$. The rate constant for the reaction is ..... $\min^{-1}$

What is the half-life period of tritium (in $years$)?

What is the value of the decay constant of a compound having a half-life time $T_{1/2} = 2.95 \text{ days}$?

Initial mass of a radioactive element is $40 \ g$. How many grams of it would be left after $24 \ years$,if its half-life period is $8 \ years$?

The half-life of $_{38}^{90}Sr$ is $20 \text{ years}$. If a sample having an initial activity of $8000 \text{ dis/min}$ is taken,what would be its activity after $80 \text{ years}$?

During a nuclear explosion,one of the products is $^{90}Sr$ with a half-life of $28.1 \ years$. If $1 \ \mu g$ of $^{90}Sr$ was absorbed in the bones of a newly born baby instead of calcium,how much of it will remain after $10 \ years$ and $60 \ years$ if it is not lost metabolically?