\"\"

\

The radio active decay of isotope formula \"\".

\

For radioactive isotope \"\" :

\

Half - life :\"\" years,

\

Initial quantity : \"\",

\

Time : \"\" years.

\

Consider \"\". \ \

\

Substitute corresponding values in above equation.

\

\"\"

\

\"\"

\

\"\"

\

\"\".

\

\"\"

\

The amount after 1000 years is 5.76 grams.