What is the half-life (in years) period of a radioactive material if its activity drops to $1 / 16^{\text {th }}$ of its initial value of $30$ years?
$9.5$
$8.5$
$7.5$
$10.5$
Write the definition of half life of radioactive substance and obtain its relation to decay constant.
Tritium has a half-life of $12.5\; y$ undergoing beta decay. What fraction of a sample of pure tritium will remain undecayed after $25\; y.$
The decay constant $\lambda $ of the radioactive sample is the probability of decay of an atom in unit time, then
The activity of a radioactive material is $6.4 \times 10^{-4}$ curie. Its half life is $5\; days$. The activity will become $5 \times 10^{-6}$ curie after $.......day$
A radioactive substance emits