Answer
There will be around 1 gram of isotope after 10 seconds.
Work Step by Step
This involves exponential decay of isotopes decreases every second..
RECALL:
Exponential growth is represented by the formula
$y=C(1-r)^x$
where
C = initial/original amount
r = decay rate
x = number of time intervals
The given situation has:
C = 5 grams
r = $15\%$ per second
x = 10 seconds
Substitute these values into the given formula above to have:
$y=5(1-15\%)^{10}
\\y=5(1-0.15)^{10}
\\y=5(0.85^{10})
\\y \approx 1$
