Answer:
A fundamental interaction of nature that acts between subatomic particles of matter. The strong force binds quarks together in clusters to make more-familiar subatomic particles, such as protons and neutrons. Something like that.
Explanation:
Putting glue on something, because once it is set in you cannot change it back.
Answer:
263.1 is exactly three half-life, so the remaining portion is (1/2 x 1/2 x 1/2) of the original sample. That's 1/8 which is 12.5%