10 minutes maximum! Can you do it in 5?

1. The binding energy per nucleon becomes relatively constant for atomic masses over about...

  • A. 15
  • B. 30
  • C. 60
  • D. 90

Q2+3. These questions are about the strong nuclear force:

2. Here are three statements about atoms.

I. The nucleus is stable despite repulsion between protons
II. The mass deficit of all nuclei indicates an attractive force exists
III. Discrete energy levels exist for electrons

Which of these statements provides evidence for the strong nuclear force?

 
  • A. I and II
  • B. I and III
  • C. II and III
  • D. all three
3. In the Rutherford-Geiger-Marsden experiment, further evidence for the strong nuclear force was discovered. Which of these correctly describes the evidence?
  • A. At low energies, fewer alpha particles were backscattered than expected
  • B. At high energies, fewer alpha particles were backscattered than expected
  • C. At low energies, more alpha particles were backscattered than expected
  • D. At high energies, more alpha particles were backscattered than expected

4. The energy of beta + particles (positrons) emitted from a given radionuclide was found to have a wide continuous range - a varying 'energy spectrum'. This evidence was used to postulate the existence of ...

  • A. antimatter
  • B. neutrinos
  • C. dark matter
  • D. particle pairs
5. The energy of alpha particles emitted from a given radionuclide was found to have 2 distinct , discrete values. This evidence was used to postulate the existence of ...
  • A. neutrons
  • B. neutrinos
  • C. nuclear energy levels
  • D. electron shells

6. The radioactive decay constant λ can be described (for small values of λt) as ...

  • A. the number of radioactive decays per unit time
  • B. the time taken for half of a sample to decay
  • C. the probability of a decay event per unit time
  • D. the number of events occuring before the activity of a sample halves

7+8. A radioactive sample with N0 atoms has a decay constant λ of 10-3 s -1.

 

 

Which of these correctly gives the time taken in seconds for the sample to decay to ½N0 and to e-1.N0?

½N0 e-1.N0
A
 1000 ln(2) 10-3 s
B
 ln(2)/1000 10-3 s
C
 1000 ln(2) 1000 s
D
 ln(2)/1000 1000 s

8. What is the activity of this sample after 2 half lives?

  • A. ¼N0
  • B. N0/1000
  • C. N0/4000
  • D. N0/250
9+10. Radioactive isotopes of two different elements X and Y are compared. Isotope X has an initial activity of A and a decay constant of λ. Isotope Y has double the half-life of X with the same initial activity A.

9. What is the decay constant of Y?

  • A. ½λ
  • B. 2λ
  • C. ½λ/ln(2)
  • D. 2 λ/ln(2)

10. Which of the following statements is correct?

  • A. Sample X has twice the initial number of atoms of Y.
  • B. The mass of sample Y is double the mass of X.
  • C. The activity of X will always be the same as the activity of Y as they both decay.
  • D. Sample X will take half as long as Y to decay to half the initial number of atoms.