he following conversion factors may help you when working this problem: Activity

Question

he following conversion factors may help you when working this problem:

Activity in becquerels (Bq) = activity in disintegrations per second (dps).

1.00 mCi=3.70×107 Bq.

Part A

Neutron activation analysis for a sample of a rock revealed the presence of 131 53I ,which has a half-life of 8.08 days . Assuming the isotope was freshly separated from its decay products, what is the mass of 131 53I in a sample emitting 1.00 mCi of radiation?

Express your answer in grams to three significant figures.

Part B

BNCT relies on the initial targeting of tumor cells by an appropriate chemical compound tagged with 10  5B, which preferentially concentrates in tumor cells. During the irradiation of the tumor site by neutrons (10n) the 10  5B absorbs a low-energy neutron (10n), and it ejects an energetic short-range alpha particle (42 or 42He) and lithium ion along with gamma radiation (). This radiation deposits most of its energy within the cell containing the original 10  5B atom. Therefore, if a higher concentration of 10  5B exists in tumor cells relative to other normal tissues, a concomitantly higher dose will be delivered to the tumor cells during neutron irradiation.

What is the nuclear reaction that takes place in the tumor cell?

Express your answer as a nuclear equation.

Explanation / Answer

I'm gonna answer Part A for now. The other part post it in another question thread:

First, let's calculate the constant K.

K = ln 2 / t1/2 = ln 2 / 8.08 = 0.0858 days-1 * 1 day/24 h * 1 h/3600 s = 9.93x10-7 s-1

Now, let's calculate the mass

m = 3.7x107 s-1 * 131 g / 9.93x10-7 s-1 * 6.02x1023
m = 8.11x10-9 g

Hope this helps

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