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1. The carbon-14 activity of a fiber from an Egyptian mummy shroud is 7.50 disin

ID: 526804 • Letter: 1

Question

1. The carbon-14 activity of a fiber from an Egyptian mummy shroud is 7.50 disintegrations per minute per gram of carbon. How old is the fiber? The half-life of C-14 is 5730 years and the activity of fresh C-14 is 15.2 disintegrations per minute per gram of carbon. 5730 ST30 1.50 t 5, 40 2. Radon in a tube is often used in cervical cancer therapy. The halflife of a radioactive radon is 3.8 days. If 11 micrograms of radon are sealed in a tube, how many micrograms remain after 21 days? tih 3.4 days 3. How long will it take before the 11ug ofradon in the previous problem is reduced to 10 micrograms.

Explanation / Answer

Q2.

HL = 3.8 days

A0 = 11 microg

Afinal = ?

apply half life equation

A = A0*(1/2)^(t/HL)

A = 11*(0.5)^(21/3.8)

A = 0.2386 mg left

Q3.

time for it in ordetr to reduce to 10^-6 microg

A = A0*(1/2)^(t/HL)

(10^-6) = (11)*(0.5)^(t/(3.8))

t = 3.8 * (ln((10^-6)/11) / ln(0.5))

t = 88.885 days