Via half-life equation we have:
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Where the initial amount is 50 grams, half-life is 4 minutes, and time elapsed is 12 minutes. By plugging those values in we get:

There is 6.25 grams left of Ra-229 after 12 minutes.
DNA is found mainly in the nucleus of the cell, while RNA is found mainly in the cytoplasm of the cell although it is usually synthesized in the nucleus.
What effect man there are a million effects the only one that arent true are fusion or fission and magnetism unless that bowling ball is iron