Q1.
Observations of the H-α line in the spectrum of a star indicate the presence of hydrogen.
The H-α line has a wavelength of 656 nm and is produced by a transition of electrons into
the −3.4 eV energy level.
Calculate the energy level that the electron moves from when emitting a photon
corresponding to a wavelength of 656 nm. Give your answer in J.
energy level ____________________ J
(Total 4 marks)
Q2.
Some energy levels of an atom of a gas are shown in Figure 1.
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.
Page 1 of 8
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.
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(3)
(b)
Determine the energy, in J, of
(i)
the photons responsible for each of the two lines shown in Figure 2,
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(ii)
levels B and C in Figure 1.
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energy of level B = ______________________________________________
Page 2 of 8
energy of level C = ______________________________________________
(5)
(Total 8 marks)
Q3.
(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?
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(1)
(ii)
Describe the process by which mercury atoms become excited in a
fluorescent tube.
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(3)
(iii)
What is the purpose of the coating on the inside surface of the glass in a
fluorescent tube?
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(3)
(b)
The lowest energy levels of a mercury atom are shown in the diagram below. The
diagram is not to scale.
Page 3 of 8
(i)
Calculate the frequency of an emitted photon due to the transition level n = 4
to level n = 3.
answer = ____________________ Hz
(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)
(Total 12 marks)
Q4.
(a)
State one similarity and one difference between an elastic collision and an inelastic
collision.
similarity ___________________________________________________________
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difference __________________________________________________________
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(2)
(b)
An unstable isotope of neodymium,
by emitting an α particle.
(i)
, decays into an isotope of cerium, Ce,
Complete the following decay equation.
(1)
Page 4 of 8
(ii)
The α particle is emitted from a stationary
nucleus at a speed of
9.3 × 106 m s−1. Calculate the recoil speed of the daughter nucleus.
recoil speed ____________________ ms−1
(2)
(iii)
Show that, when a stationary
the
nucleus decays, the kinetic energy of
recoiling cerium nucleus is only about 3% of the kinetic energy of the emitted α
particle.
(3)
(Total 8 marks)
Q5.
(a)
Sketch a graph of binding energy per nucleon against nucleon number for the
naturally occurring nuclides on the axes given in the figure below. Add values and a
unit to the binding energy per nucleon axis.
(4)
Page 5 of 8
(b)
Use the graph to explain how energy is released when some nuclides undergo
fission and when other nuclides undergo fusion.
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(3)
(Total 7 marks)
Q6.
The table below gives the values for the activity of a radioactive isotope over a period of a
few minutes.
time/s
activity/Bq
(a)
0
60
120
180
240
300
480
366
280
214
163
124
Complete the graph below by plotting the remaining points and drawing an
appropriate curve.
Page 6 of 8
(3)
(b)
Use the graph to determine the half-life of the isotope.
half-life ____________________
(3)
(c)
Initially there were 1.1 × 105 atoms of the isotope present. Calculate the decay
probability of the isotope.
decay probability ____________________
(2)
(Total 8 marks)
Q7.
(a)
Complete the table by naming one example of each type of particle.
type of particle
example
lepton
baryon
meson
(3)
(b)
The following reaction cannot occur.
π+ + n → p + π–
(i)
State and explain which conservation law would be broken by this reaction.
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Page 7 of 8
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(2)
(ii)
State and explain one conservation law that would not be broken in this
reaction.
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(1)
(c)
Describe what happens when a proton and an antiproton collide.
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(2)
(Total 8 marks)
Page 8 of 8