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Homework Help: Radioactive decay

  1. Sep 24, 2010 #1
    1. The problem statement, all variables and given/known data

    Complete the following decay equations by inserting the missing particle or nuclide information. Identify each type of decay.

    i) 90?Sr = ?39Y + ? + ?

    ii) 22?Na = ??Ne + β+ + ? + energy

    iii)24294Pu = ??? + alpha + ?

    iv) 235?U = 91?Sr + 141?Xe + ?

    v) 0-1e + 0+1e → ?

    3. The attempt at a solution

    i) 9038Sr = 8939Y + β- + ? this is beta decay.
    - note, lost 1 nucleon. is this ? just 1n?

    ii) 2211Na = 2010Ne + β+ + ? + energy also beta decay
    - note, lost 2 nucleons. is this ? just 21n?

    iii) 24294Pu = 23892U + alpha + ? alpha decay

    iv) 23592U = 9138Sr + 14154Xe + ? fission?

    v) i have no idea.

    - Just looking at that, there seems to be an extra ? for each decay equation. in my text throughout theres only the decay pronumeral in the products, not something extra as well. so im not really sure what is meant to go in there?
    - Also im not sure about the relevance of the energy is ii) since all of these decays emit energy anyway.
    - iv) doesnt look to be any kind of decay, it seems to represent fission. which would make that '?' 31n?
    - and v) i have no idea what the result of an electron positron bond is.
  2. jcsd
  3. Sep 24, 2010 #2
    v) Matter and antimatter combining to result in something that, according to the superscript and subscript, will have no mass and no charge. That tells us what comes out of it.
  4. Sep 24, 2010 #3
    ohhh... becomes 2 neutrinos where a neutrino is a particle with no charge and mass equal to an electron?... that would conserve mass and charge...

    and your not sure about the other '?' either?
  5. Sep 25, 2010 #4
  6. Sep 26, 2010 #5

    just so my thread goes to the top of the list again so more people see it. haha
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