Sample Test question on Radioactivity

[physstudent.4]

Homework Statement

The activity of carbon, due to the decay of C14, is 16 disintegrations per minute per gram of carbon. The atomic weight of naturally occurring carbon is 12 u. What is the ration of C14 to C12 in the CO2 of the atmosphere? The half life of C14 is 5730 years.

Homework Equations

t(half life) = ln(2)/ lambda
N = N(initial) e^ (-lambda * t)
R = -dN/dt

The Attempt at a Solution

I just don't know how to attempt this problem without having a time frame. I don't expect the answer, but if there is an equation I missed that is helpful, or something I seem to not understand, I would greatly appreciate being told! Thanks!

 

[Redbelly98]

I had to think about this one for a while. Hope this helps get you going:

Homework Statement

The activity of carbon, due to the decay of C14, is 16 disintegrations per minute per gram of carbon. The atomic weight of naturally occurring carbon is 12 u.

Okay, based on this information, how many disintegrations per minute are there in 1 mole of naturally occurring carbon?

What is the ration of C14 to C12 in the CO2 of the atmosphere? The half life of C14 is 5730 years.

Based on this information, how many disintegrations per minute are there in 1 mole of C14?

 

[physstudent.4]

Ah, thank you!