WAEC Physics 2015 Theory — Question 24
Question 24 of 26 from the West African Examinations Council (WAEC) Physics 2015 Theory paper, with the correct answer and a full explanation.
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12(b). A radioactive isotope of Americium (Am-241) decays into a nucleus of Neptunium (Np-237) and an alpha (α) particle, according to the equation: ₁₉₅⁴¹Am → ₉₇²³⁷Np + ₐᵇα. State the number of neutrons in the nucleus of Americium-241, and determine the values of a and b.
Model answer
Number of neutrons = nucleon number − proton number = 241 − 95 = 146. Since an alpha particle is a helium nucleus ⁴₂He, a = 4 (mass number) and b = 2 (proton/atomic number).
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