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## Homework Statement

I'm not sure if whether mass changes when atoms decay. Does emitting alpha/beta/gamma cause the atoms to lose mass? I don't know

## Homework Equations

Uranium-235 has a half life of 7.35x10^5 years and uranium 238 has a half life of 4.5x10^6 years. Compare the two isotopes of uranium, given that they both have the same number of atoms.

a) Which sample would have the greater weight?

b) which sample would have the greater number of decays per second?

## The Attempt at a Solution

For a) I'm not really sure but I think it would be the U-238 because it has the greater half life

For b) I'm not sure if this is right, if shorter half-life means greater decays per second. But I think it should be the U-235