9.
S1: One of the many young scientists who chose to throw in their lot with Rutherford was an Oxford physical chemist, Frederick Soddy.
S6: We now know that Gamma rays are a particularly fierce form of X-rays.
P: His association with Rutherford lasted only two years, but that was long enough to change the whole face of physics.
Q: He was just 23.
R: They found that thorium changed into a new element, thorium X, and in the process gave off what was apparently a gas and at the same time a third type of ray, which they named after the Greek letter ‘Gamma’.
S: When he teamed up with Rutherford, they investigated thorium which, as Marie Curie had shown, was radioactive.
The proper sequence should be