physics

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1)7Be decays with a half-life of about 53 d. It is produced in the upper atmosphere, and filters down onto the Earth's surface. If a plant leaf is detected to have 300 decays/s of 7Be, how many days do we have to wait for the decay rate to drop to 13.6/s? Do not enter units.
b.Calculate the initial mass of 7Be on the leaf.
2) What is the energy of the alpha particle emitted in the decay 232U ==> 228Th + alpha?

3) How much energy is released when a neutron, decays by beta- emission?

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did anyone get the answer to this problem?

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