Back
Problem 90
The nuclide 6Li reacts with 2H to form two identical particles. Identify the particles.
Problem 91
The half-life of 238U is 4.5⨉109 yr. A sample of rock of mass 1.6 g produces 29 dis/s. Assuming all the radioactivity is due to 238U, find the percent by mass of 238U in the rock.
Problem 92
The half-life of 232Th is 1.4⨉1010 yr. Find the number of disintegrations per hour emitted by 1.0 mol of 232Th.
- A 1.50-L gas sample at 745 mm Hg and 25.0 °C contains 3.55% radon-220 by volume. Radon-220 is an alpha emitter with a half-life of 55.6 s. How many alpha particles are emitted by the gas sample in 5.00 minutes?
Problem 93
Problem 94
A 228-mL sample of an aqueous solution contains 2.35% MgCl2 by mass. Exactly one-half of the magnesium ions are Mg-28, a beta emitter with a half-life of 21 hours. What is the decay rate of Mg-28 in the solution after 4.00 days? (Assume a density of 1.02 g/mL for the solution.)
- When a positron and an electron collide and annihilate each other, two photons of equal energy are produced. What is the wavelength of these photons?
Problem 95
Problem 96
The half-life of 235U, an alpha emitter, is 7.1⨉108 years. Calculate the number of alpha particles emitted by 1.0 mg of this nuclide in 1.0 minute.
Problem 97
Given that the energy released in the fusion of two deuterons to a 3He and a neutron is 3.3 MeV, and in the fusion to tritium and a proton it is 4.0 MeV, calculate the energy change for the process 3He + 1n → 3H + 1p. Suggest an explanation for why this process occurs at much lower temperatures than either of the first two.