A radioactive isotope has a half-life of 72.0 min . A sample is prepared that has an initial activity of 1.60×1011 Bq . A) How many radioactive nuclei are initially present in the sample? B) How many are present after 72.0 min? C) What is the activity after 72.0 min? Express your answer in becquerel.   D) How many are present after 144 min?   E) What is the activity after 144 min? Express your answer in becquerel.

Determine the half-life (in s) of a radioactive sample that has a decay rate of 3.30 ✕ 1011 Bq when it contains 1.70 ✕ 1015 nuclei.  s

A. B. Use the worked example above to help you solve this problem. The half-life of the radioactive nucleus 226 Ra is 1.6× 10³ yr. If a sample initially contains 3.34 x 1016 such nuclei, determine the following: 88 (a) the initial activity in curies μCi (b) the number of radium nuclei remaining after 4.5x 10³ yr nuclei (c) the activity at this later time μCi Use the values from PRACTICE IT to help you work this exercise. (a) Find the number of remaining radium nuclei after 3.10 x 10³ yr. N = nuclei (b) Find the activity at this time. R = μCi

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10. The radioactive isotope (82Sr) has a half-life of 25.4 days. A sample containing this isotope has an initial activity at (t = 0) of 4.50 × 108 Bq. Calculate the number of nuclei that will decay in the time interval between t₁ = 80.0 hours. for ssi nuclei ssf624 50 ssfo 30.0 hours and t2 sf60 s 60 ssf6

A moon rock collected by a U.S. Apollo mission is estimated to be 3.90 billion years old by uranium/lead dating. Assuming that the rock did not contain any lead when it was formed, what is the current mass of 20°Pb in the rock, if it currently contains 1.340 g of 238 U? The half-life of 238U is 4.47 × 10° years. 206Pb mass: 1.1 Incorrect

Problems:1. Living matter has 1.3 x 10-10 % of its carbon in the form of C-14 which has a half-life of 5730 yr. A mammoth bone has a 300-g sample of carbon separated from it, and the sample is found to have an activity of 20 decays per second. How old is the bone?

A radioactive isotope has a half-life of 72.0 min. A sample is prepared that has an initial activity of 1.60×1011 Bq A) How many radioactive nuclei are initially present in the sample? B) How many are present after 72.0 min? C) What is the activity after 72.0 min? Express your answer in becquerel. D) How many are present after 144 min? E) What is the activity after 144 min? Express your answer in becquerel.

Problem 8:  In a living organism, a fixed fraction 1.30 × 10-12 of 12C is the radioactive isotope 14C, which has a half life of 5730 y.     What is the activity of the 14C in 1.8 g of 12C found in living tissue in Bq?Numeric   : A numeric value is expected and not an expression.R = __________________________________________

The age of wine can be determined by measuring its radioactive tritium content. i. How many protons, electrons, and neutrons are in tritium (3H)? ii. The half life of tritium is 12.5 years. What is the age of a wine that has only 43% of the tritium activity of a freshly bottled sample? Please explain why your answer makes sense.