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Topic & Physcis

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Discrete Energy level
1. Electrons orbit the nucleus at specific energy levels, or shells. An electron falling from a high
energy level to a lower level will have




A. absorbed a photon
B. emitted a photon
C. absorbed a neutrino
D. emitted a neutrino
2. The diagram shows electron energy levels within a hydrogen
atom. Of the 4 possible transitions listed below, the transition that
will give rise to an emission spectral line of the shortest wavelength
is




A. from n=1 to n=2
B. from n=2 to n=3
C. from n=3 to n=2
D. from n=2 to n=1
1. Some energy levels of an atom of a gas are shown in Figure 1.
When a current is passed through the gas at low pressure, a line spectrum is
produced. Two of these lines, which correspond to transitions from levels B and C
respectively to the ground state, are shown in Figure 2.
(a)
Describe what happens to an electron in an atom in the ground state in order
for the atom to emit light of wavelength 4.0 × 10–7 m.
You may be awarded marks for the quality of written communication in your
answer.
[3]
(b)
Determine the energy, in J, of
(i)
the photons responsible for each of the two lines shown in Figure 2,
(ii)
levels B and C in Figure 1.
[5]
2.
(a)
A fluorescent tube is filled with mercury vapour at low pressure. In order to
emit electromagnetic radiation the mercury atoms must first be excited.
(i)
What is meant by an excited atom?
[1]
(ii)
Describe the process by which mercury atoms become excited in a
fluorescent tube.
[3]
(iii)
What is the purpose of the coating on the inside surface of the glass in
a fluorescent tube?
[3]
(b)
The lowest energy levels of a mercury atom are shown in the diagram below.
The diagram is not to scale.
(i)
Calculate the frequency of an emitted photon due to the transition level
n = 4 to level n = 3.
[3]
(ii)
Draw an arrow on the diagram above to show a transition which emits a
photon of a longer wavelength than that emitted in the transition from
level n = 4 to level n = 3.
[2]
Radioactive Decay
3. Which of these word equations summarises beta decay ( β - ) ?




A. neutron
B. proton
C. neutron
D. proton
proton + beta particle + neutrino
neutron + beta particle + neutrino
proton + beta particle + antineutrino
neutron + beta particle + antineutrino
4. When Uranium decays it emits an alpha particle, forming an isotope of Thorium. Which of the
following decay equations is correct?
A.
238
U
92
232
2
Th + α
90
2
B.
238
U
92
236
2
Th + α
90
2
C.
238
U
92
234
4
Th + α
90
2
D.
238
U
92
232
4
Th + α
90
2
5. Nuclides and isotopes have different definitions but are often confused. The correct definitions are:
Nuclides
Different proton AND neutron
A
numbers
Different proton AND neutron
B
numbers
Isotopes
Same number of protons, different number of
neutrons
Same number of neutrons, different number of
protons
Same number of protons, different number of
C Different proton OR neutron numbers
neutrons
Same number of neutrons, different number of
D Different proton OR neutron numbers
protons
6. Which of the following graphs shows how the activity of a sample varies with time?
A.
B.
C.
D.
7. Using the correct graph above, what is the half-life of this isotope?




A. 2 days
B. 4 days
C. 6 days
D. 8 days
8. A sample of 64g of radioisotope has a half life of 6 hours. After 2 days the mass of original
isotope remaining is




A. 8g
B. 0.5g
C. 0.25g
D. 0.125g
9. Two radioisotopes emit gamma rays of different frequencies. The gamma ray from isotope X
has f=1020 Hz and from Y, f=1021 Hz.
Which of these correctly decribes the gamma rays emitted?
Gamma ray with shortest wavelength Gamma ray with highest energy
A. X
X
B. X
Y
C. Y
X
D. Y
Y
10. Binding energy per nucleon is usually stated as a positive value. When helium nuclei fuse
together to form beryllium nuclei in the centre of a star, how does the binding energy and the
mass defect change?




A. the binding energy per nucleon inceases and the mass defect increases
B. the binding energy per nucleon deceases and the mass defect increases
C. the binding energy per nucleon inceases and the mass defect decreases
D. the binding energy per nucleon deceases and the mass defect decreases