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المسأله الاولى
-The half-life of radioactive zinc 72 is 50 h. Find the percentage loss of activity which occurs in a sample of zinc 72 in 1.0h.
المسألة الثانية

Many textbooks and reference books use the atomic mass unit (a.m.u) and the electron volt (e V) as units of energy. These are not SI units, but you must be able to use them. Given that 1 a.m.u is 1/12 th of the mass of the carbon atom 12 C, and that an eV is the
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energy gained by a charge equal to that on an electron moving through a p.d. of 1.0 volt, Find:

(a) how many joules are equivalent to 1 a.m.u.
(b) how many joules are equivalent to 1 eV
(c) how many joules are equivalent to 1 MeV
(d) how many MeV are equivalent to 1 a.m.u

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