10. A student writes the beta decay of carbon-14 as follows: 14 CO+B- Four of her classmates pointed out that the equation is incorrect for the following reasons: Classmate A: There is a missing decay particle. Classmate B: The daughter nucleus is incorrectly identified. Classmate C: The parent nucleus has an incorrect number of protons. Classmate D: The number of protons of the daughter nucleus must be 1 less than that of the parent nucleus. Who among the classmates has/have given the correct statement/s?

2a) What is the average 226Ra alpha particle heat power output of 1 tonne of New Zealand soil? 2b) Why does soil not heat up from the energy of alpha decay? 2c) In our soil 226RA is, on average, found at a concentration of around 1 part per million, by mass. How many grammes of 22°RA are in 1 tonne of soil? 2d) How many tonnes of soil would need to be processed to obtain sufficient 226Ra to create a sample with a 1W alpha energy output? Is this practical? 2e) 22°Ra is part of the decay chain of 238U. Will the concentrations of the other decay products (in ppm, say) be identical to that of 22°RA? Explain your reasoning. 2f) Explain how radioactive material in New Zealand soil could get in to the human body and discuss the health risks of alpha emitting radionuclides.

The half-life for the a decay of uranium 2U is 4.47 x 10° yr. Determine the age (in years) of a rock specimen that contains 48.6% of its original number of U atoms. t-Number i Units

4. Technitium-99m* is a gamma-emitter. Write the balanced nuclear equation for y-decay of technitium- 99m*. Note that m* means that this isotope is in a high-energy state and releases energy in the form of gamma radiation.

b) Complete the following decay reaction by identifying both the temporary nucleus (??) and the end product (?) that it decays into. In this case, sodium-23 is bombarded with protons, forming a short-lived nucleus which quickly undergoes alpha decay. 2Na+H → (??) → (⁄?) + ª Enter the chemical symbol for the temporary nucleus: Enter the mass number for the end product, A = Enter the atomic number for the end product, Z = Enter the chemical symbol for the end product: AV A/ AV 10

3C. Write the equation for the beta-positive decay of Potassium-40. b) Write the element that is formed in the beta-positive decay of Potassium- 40. Your answer

What is the nuclear equation for Th (beta decay)? (Just enter a, b, c or d without a period). 90 235 a. 334TH 90 b. 234 Th 234 Ac + e 90 89 4 Pa + °1e 234 c. 30 Th d. 84TH - 1 Pa + °e 90 O a O b O c « Previous MacBook Pro

The curve to the right shows the radioactive decay of a particular sample of a nucleus called Element 9. A particular nucleus survives for the first 10 hours, what is the probability that particular nucleus of Element 9 will decay between 10 hours and 20 hours? N 400 - a. 50.0%. b. 75.0%. 100- c. 25.0%. d. above 98%. 5 10 15 t (in hrs) e. 86.5%.

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9. A rock that contains 1.2x10-12 mol of 232Th (t1/2 = 1.4x1010 yr) has 4.2x105 fission tracks, each track representing the fission of one atom of 232Th. How old is the rock?