How much of one gram of radium-226 will remain unchanged after four half-lives?

What must happen before a body cell can begin mitotic cell division

In the 1800s, one of the statements in john dalton's atomic theory was that atoms are indivisible. later experimental evidence led to the discovery of subatomic particles such as neutrons, electrons, and protons. what happened to the indivisible atom part of dalton's atomic theory, and why?

No copying 15 pts how does a free-body diagram tell you about the net force on an object?