A laboratory student prepared a 0.00155 M KBr solution with a small amount of radioactive 77Br (t_1/2 = 57.04 h). She recorded the activity of the solution as 0.127 mCi/mL. She used 25.0 mL of this solution to precipitate an unknown metal Y as YBr. She mixed the KBr solution with 25.0 mL of 0.00234 M YNO₃ solution. She removed the precipitate by filtration and the activity of the obtained filtrate after 5 hours was 0.0156 mCi/mL. Calculate the molar concentration of Y⁺, Br⁻, and the solubility product of YBr.

Americium is a synthetic radioactive element. An isotopic mixture was made in a laboratory that had equal amounts of ²⁴¹Am and ²⁴³Am in it. After some time, the observed ratio of the two isotopes was 0.158. The half-lives of ²⁴¹Am and ²⁴³Am are 432.2 h and 7370 h, respectively. How old is the mixture after the change?

The radioactivity in a soil sample that comes from the decay of uranium isotopes is 662 pCi/mg. Calculate the number of disintegrations in 1 mg of soil in 1 hour. Assuming that the major radioisotope is ²³⁸U (t_1/2 = 4.468×10⁹ y), how many ²³⁸U atoms are there in 2.5 mg of soil?

Calculate the time it will take for the amount of Niobium-92 to reach 25.0% of its initial amount. The half-life of Nb-92 is 34.7 million years.

The Bedrock in Hudson Bay, Canada is the oldest known rock bed on the planet. Using uranium/lead radiometric dating, it has been found to be 4.28 billion years old. If we assume that the rock only contained ²³⁶U in the beginning, what would be the mass of ²⁰⁶Pb in a sample of the rock if it currently contains 1.500 g of ²³⁶U? (The half-life of  ²³⁶U is t_1/2 = 4.47 x 10⁹ years.)

9.01333 amu, 10.01294 amu, and 11.00931 amu are the nuclear masses for ⁹B, ¹⁰B, and ¹¹B, respectively. Determine the nuclei with the highest nucleon binding energy from the given

Part A. What is the amount of energy absorbed by a 65 kg human who was exposed to 25.9 rad of radiation?

Part B. What is the amount of energy absorbed by a 65 kg human who jumped from a stool with a height of 0.45 m to the floor assuming the entire force of the fall
is taken in by the person?

Part C. How does the amount of energy in part a differ from part b?

Find the mass defect (in amu) and binding energy (in kJ/mol) of ⁸⁴Mo (atomic mass = 83.9401). Determine whether it is more stable than ⁷⁹Zr with a binding energy of 6.31 x 10¹⁰ kJ/mol. Use c = 299792458 m/s.

Find the missing species in the following nuclear equation and calculate the energy change per mole of Ar-34: 

³⁴₁₈Ar + _____ → ³¹₁₆S + ⁴₂He

m_Ar-34 = 33.9802 amu

m_S-31 = 30.9795 amu

m_He-4 = 4.0026 amu 

Given that the atomic masses of Hydrogen-3, Beryllium-9, and Lithium-7 are 3.0160493 amu, 9.0121821 amu, and 7.0160040 amu, respectively, find the nuclear binding energy per nucleon (in 6 s.f.) for each of the following isotopes:

(i) Hydrogen-3

(ii) Beryllium-9

(iii) Lithium-7