Posted by **tina** on Thursday, February 23, 2012 at 2:44pm.

If 30% of a sample of radioactive isotope decays in 24 hrs, what is the half-life?

How do i know which order to use? and do I convert hr to mins or seconds?

Pls help for my exam tomorrrow

- Chemistry -
**DrBob222**, Thursday, February 23, 2012 at 3:00pm
ALL radioactive decay problems are first order so you use ln(No/N) = kt.

If you want the half life in hours, leave it as is. If you want it in min or seconds, then convert the 24 hours to some other unit. Since the problem doesn't specify, I would leave it as 24 hours.

- Chemistry -
**Anonymous**, Monday, April 2, 2012 at 6:10pm
In n=-kt +in,no

## Answer This Question

## Related Questions

- chemistry - a radioactive material is undergoin nuclear decay. After 40 minutes...
- Chemistry - Gallium65, a radioactive isotope of gallium, decays by first order-...
- Physcis 30 - Q1) If there are 100 radioactive atoms with a half-life of 30 ...
- Chemistry - As a sample of the radioactive isotope 131 I decays, its half-life a...
- Chemistry - A 208 g sample of sodium-24 decays to 13.0 g of sodium-24 within 60....
- Radioactivity or science - A radioactive isotope source has a mass of 120ug. If ...
- Radioactivity - How are the terms "activity" and "becquerel" related? A ...
- physics - Suppose 32000 radioactive nuclei are in a sample. About how many ...
- chemistry -- radioactive decay - suppose you have a 150 gram sample of ...
- Chemistry - If a 100.0 gram sample of a radioactive isotope goes through three ...

More Related Questions