Posted by **koteswaramma** on Friday, August 15, 2014 at 9:22am.

a radioactive substance decays 10% in 5 days. The amount remains after 20 days?

- chemistry -
**DrBob222**, Friday, August 15, 2014 at 2:20pm
You need to determine k, the rate constant and I would do it this way.

ln(No/N) = kt

No = 10

N = 90

k = solve for this

t = 5 days.

Then knowing k, redo

ln(No/N) = kt

No = 100

N = Solve for this.

k from above

t = 20 days

## Answer This Question

## Related Questions

- College Algebra - A radioactive substance decays in such a way that the amount ...
- Math/Calculus - After 5 days, a particular radioactive substance decays to 37% ...
- Physics - A radioactive substance decays from 2.0kg to 1.6kg in 156 days. How ...
- Calculus - Santr 109 (a fictitious substance) decays by about 6% every day. How ...
- Science - If 15% of the radioactive material decays in 5 days, what would be the...
- Calculus - The radioactive element polonium decays according to the law given ...
- College Algebra - A radioactive substance decays in such a way that the amount ...
- Algebra I - A sample of radioactive material weighing 45 grams has a decay rate ...
- Alegbra - Andrew measures the amount of a very unstable substance to be 100 ...
- Algebra 2 help... - A half life of a certain radioactive is 36 days. An initial ...

More Related Questions