[hameeda]

Which set does each of thees living things fit in to : lobster,butterfly,dog,human,fir tree,daffodil,primrose?

[xOhMy876xx]

Half-life is the amount of time it takes for half of a given number of molecules to degrade. For example, the half-life of 10046Pd is 4 days. If you start with a given number of 10046Pd atoms, then at the end of 4 days, n/2 of those atoms will have decayed into another element or isotope. At that same time you will have n/2 10046Pd atoms left. At the end of four more days, n/4 atoms will have decayed into another element or isotope. At the same time, n/4 of the 10046Pd atoms will be left. How many atoms will remain at the end of another 4 days? (Answer: n/8 where n = number of atoms you started with.)

Review Topic 12 if you need more help calculating the half-life of a radioactive element.

Complete the following problems:

1. The half-life of 9142Mo is 15.5 minutes. If you start with 3.5 x 1022 atoms of 9142Mo, how many atoms will remain after 31 minutes?

Hint: There are two steps in this problem.

Step 1: You first have to identify how many half-lives 31 minutes is. To do this take 31 min. and divide by 15.5. (31 min / 15.2 min = 2 half-lives). So the 9142Mo will go through 2 half-life cycles in 31 minutes, leaving n/4 atoms behind.

Step 2: Now you are ready to identify how many atoms will remain at the end of 31 minutes.

Answer:






2. The half-life of 31H is 12.26 years. If you start with 2.0 x 1015 atoms of 31H, how many atoms will remain after 36.78 years?

Answer:






3. The half-life of 6932Ge is 30 hours. If you start with 3.0 X 105 atoms of 6932Ge, how many atoms will remain after 120 hours?

Answer:





4. The half-life of 146C is 5730 years. If you start with 2.5 X 109 atoms of 146C, how many atoms will remain after 28,650 years?

Answer:





5. The half-life of 198O is 29.1 seconds. If you start with 1.5 x 1022 atoms of 198O, how many atoms will remain after 4 minutes and 51 seconds?

Answer:

[xOhMy876xx]

You need help

[baseballneil]

:( Sorry

[mckiep09]

Sorry:(

[Unknown008]

What the... what's going on here??

Hey, why bring up a post of so long time ago? By the way, xOhMy876xx, you need to post that in the physics topic. Here's biology.