If it takes 480 J to raise temperatre of a piece of copper from 20 to 60 Celsius, what is the mass (g) of the copper? Specific heat of copper is 0.4 J/gc 10
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the answer is learned

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.

your parents i think this could be it