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6. How do nuclei become more stable?
- Undergo fission
- Emit alpha, beta and gamma radiation
- Emit alpha and beta radiation
7. Why is a vacuum needed for the alpha scattering experiment?
- Alpha particles scatter off of air particles
- Alpha particles would be slowed down
- Alpha radiation might come from the air particles
8. What is the half life of a nucleus?
- Number of nuclei left after half a minute
- Time for activity to decrease by a half
- Time for activity to decrease to zero
9. What is understood about the atom when some alpha particles deflect by more than 90 degrees
- The nucleus is negative
- The nucleus is positive
- The nucleus of gold is larger than alpha radiation
10. What is understood about the atom when most alpha particles pass through gold foil
- Most of the mass of an atom is concentrated in the nucleus
- Most of the mass of an atom is spread out
- Nuclei are positive
11. Why do substances for medical tracers have a 6 hour half life?
- Radioactive substance will be digested before it fully decays
- Stable enough to make measurements and decays away after use
- Short enough that radiation won't reach sensitive parts of the body
12. Why do nuclei emit photons?
- They form a more stable isotope
- They have too much energy, which photons take away
- Makes them change into another element
13. Why is alpha radiation not used for medical tracers?
- Can't penetrate the skin
- Not very stable
- Emits too much energy
14. What is the range of a beta particle?
- Up to a meter
- A few cm
- Infinite
15. What are the effects of ionisation on the body?
- Destroys cell membrane and damages DNA
- Destroys cell membrane but DNA is unaffected
- Damages DNA but cell membrane is unaffected
16. In radioactivity what does the symbol lambda stand for?
- Wavelength
- Probability that a nucleus decays per second
- Probability that a nucleus decays per kilogram
17. Before Rutherford's experiment what was the popular structure for the atom?
- Quantum
- Plum pudding
- Nuclear