Radioactive Decay and Radiation Behavior

The video tutorial covers the 2011 atoms and radioactivity exam, focusing on atomic models, Rutherford's gold foil experiment, and the behavior of alpha, beta, and gamma radiation in magnetic fields. It explains the concept of radioactive decay, half-life, and provides calculations related to iodine-131. The tutorial also discusses the Plum Pudding model and the discovery of the nucleus.

What is the main feature of Thompson's Plum Pudding model?

• Electrons orbiting a central proton

• A positively charged mass with embedded electrons

• A neutron core with surrounding electrons

• A dense nucleus with orbiting electrons

What observation from Rutherford's experiment suggested that most of the atom is empty space?

• Most alpha particles passed through the gold foil unaffected

• Alpha particles were deflected at large angles

• Alpha particles were absorbed by the gold foil

• Alpha particles were reflected back

Why did Rutherford use a vacuum chamber in his experiment?

• To increase the speed of alpha particles

• To enhance the visibility of the zinc sulfide screen

• To cool down the apparatus

• To prevent air from affecting the alpha particles

How does beta radiation behave in a magnetic field compared to alpha radiation?

• It is deflected in the opposite direction and more sharply

• It is not deflected at all

• It is deflected less than alpha radiation

• It is deflected in the same direction as alpha radiation

What is the charge of gamma radiation?

• Variable

• Neutral

• Negative

• Positive

What happens to the atomic number during alpha decay?

• It increases by two

• It decreases by two

• It remains unchanged

• It decreases by one

During beta decay, what change occurs in the nucleus?

• Two protons are lost

• A neutron is converted into a proton

• A proton is converted into a neutron

• Two neutrons are lost

What is the half-life of a radioactive nuclide?

• The time it takes for half of the nuclide to decay

• The time it takes for the nuclide to completely decay

• The time it takes for the nuclide to become stable

• The time it takes for the nuclide to double in mass

If a sample of iodine-131 starts with a count rate of 40, what will the count rate be after 16 days?

• 40

• 5

• 20

• 10

After 24 days, what is the expected count rate of iodine-131 if it starts at 40 counts per second?

• 5

• 10

• 20

• 40