$\"\"$

\

The exponential decay function is $\"\"$ .

\

The initial amount of dinitrogen pentoxide $\"\"$ .

\

decomposes to $\"\"$ in $\"\"$ minutes.

\

Hence, $\"\"$ and $\"\"$ .

\

Substitute all the values in $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

Therefore,the decay constant is $\"\"$

\

$\"\"$

\

The equation is $\"\"$ .

\

Find the amount of dinitrogen pentoxide will remain after $\"\"$ minutes.

\

Substitute $\"\"$ and $\"\"$ and $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

Therefore,the amount of dinitrogen pentoxide after $\"\"$ minutes $\"\"$ .

\

$\"\"$

\

Fid the time to reach dinitrogen pentoxide level to $\"\"$ .

\

Substitute $\"\"$ and $\"\"$ and $\"\"$ in $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

Therefore, the dinitrogen pentoxide level reaches $\"\"$ after $\"\"$ .

\

$\"\"$

\

The amount of dinitrogen pentoxide after $\"\"$ minutes $\"\"$ ..

\

The dinitrogen pentoxide level reaches $\"\"$ after $\"\"$ .