a. Bismuth-214 decays by alpha emission with a half-life of 19.7 minutes. If 15.0 grams of...

a. Bismuth-214 decays by alpha emission with a half-life of 19.7 minutes. If 15.0 grams of Bismuth-214 is placed in a sealed vessel, what mass of the Bismuth will have decayed after 35.0 minutes?

b. How long will it take for a sample of carbon-14 to decay such that only 70% of the original sample of carbon-14 remains?

c. In a process called "positron-electron annihilation," a positron collides with an electron, and both particles are destroyed. During this process, the total mass of both particles is completely converted to energy in the form of gamma radiation. Determine the total energy given off when one positron collides with one electron resulting in annihilation. (Note: mass of positron = mass of electron = 0.000549 amu)

Expert Solution

c) Annihilation process makes two photons.

Let us assume the kinetic energy of each particle as 1.00 MeV.

The total energy of electron and positron is 2 × 1.00MeV + 2 × 0.511MeV = 3.02MeV . (Rest energy of electron is 0.511MeV .)

queen_honey_blossom answered 2 years ago

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