The half-life of a radionuclide is $69.3 \text{ minutes}$. What is its average life (in minutes)?

$A$ certain nuclide has a half-life period of $30 \ min$. If a sample containing $600$ atoms is allowed to decay for $90 \ min$,how many atoms will remain (in $atoms$)?

If the half-life of a certain radioactive nucleus is $1000 \ s,$ the disintegration constant is

The half-life period for a radioactive substance is $15$ minutes. How many grams of this radioactive substance is decayed from $50$ g of substance after $1$ hour?

Radioactivity of a sample $(Z=22)$ decreases by $90 \%$ after $10 \ years$. What will be the half-life of the sample (in $years$)?

The half-life of a radioisotope is $4 \ hours$. If the initial mass of the isotope is $200 \ g$,then the mass remaining after $24 \ hours$ will be ....... $g$.