c) Complete the following decay reaction to show sodium-24 undergoing B decay. First identify the unknown daughter nucleus (?), ar subatomic particle that completes the reaction. Na → (?) + v + (subatomic particle) 11 Enter the mass number A E Enter the atomic number Z = Enter the chemical symbol: Name the subatomic particle: and then name the A 17

Select the product nucleus resulting from the alpha particle decay of: 237 Np 93   a. 233 Pa 91   b. 237 Pa 91   c. 233 Np 93   d. 237 Pu 94

An unstable isotope of cobalt, 60Co, has one more neutron in its nucleus than the stable 59Co and is a beta emitter with a half-life of 5.30 years. This isotope is widely used in medicine. A certain radiation source in a hospital contains 4.20×10−2g of 60Co A) What is the decay constant for that isotope? Express your answer with the appropriate units.  B) How many atoms are in the source? C) How many decays occur per second? Express your answer as a number of decays per second. D) What is the activity of the source, in curies? Express your answer in curies.

S Thorium-234 is a radioactive element that has a decay constant of 3.33 × 10-7s ¹. It decays by beta-decay with an energy of 270 keV. A sample of pure Th-234 has an initial activity of 8.56 × 10¹3 Bq. i) Calculate the initial number of atoms present. ii) Calculate number of days taken for the activity to drop to one-sixteenth of the initial activity. iii) Calculate the initial mass of the sample, and estimate the reduction in mass at the time calculated in (ii).