Download 688 Chapter 21 Review - District 196 e

Chapter 21 Review
Conceptual Questions
9. Which of the following phases of matter is most
abundant among the visible matter in our
universe? Explain where it is usually found.
a) solid b) liquid c) gas d) plasma
Section 21.1
1. The element hydrogen is
a. More abundant than helium in the universe
b. Less abundant than helium in the universe
c. Always found combined with carbon as methane
in molecular clouds
d. Always found combined with nitrogen as
ammonia in molecular clouds
Section 21.2
10. Suppose there were planets around a star that was
larger and hotter than the Sun. Would you expect
to find an Earth-like planet closer or farther away
form the star? Give the reasoning behind your
answer.
2. The Big Bang theory is supported by which of the
following observations?
a. Stars like the Sun are about average in size.
b. Distant galaxies are all receding from us.
c. The Sun carries out nuclear fusion reactions in
its core.
d. Stars tend to be grouped into large collections
called galaxies.
11. Explain how the “frost line” affected the formation
of the inner and outer planets.
3. Are chemical reactions likely to occur in the Sun?
Why or why not?
14. What is the meaning of the term accretion in the
context of the formation of the solar system?
4. Research two examples of plasmas you might find
on Earth. What gasses are involved? What is the
average temperature?
15. What happens to all the energy absorbed by a
planet from the Sun?
5. A person tells you that they believe combustion of
flammable gasses make heat in the Sun just as a
fireplace makes heat on Earth. Write one
paragraph agreeing or disagreeing and state at
least 2 reasons to support your position.
6. Explain why a single nuclear fusion reaction like
the one below does not occur, or occurs so rarely
that it is completely unimportant in the Sun.
1
1
1
1
4
H + H + H + H = He + 2ν e + 2e
+
7. Describe the origin of the element, oxygen as it
appears on Earth. Where do oxygen atoms come
from? Are they made on Earth?
8. Name at least three major substances in the
interstellar medium. Identify them as elements or
compounds.
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12. List three of the most important differences
between the inner and outer planets.
13. Which planet has the highest average surface
temperature? Is this planet the closest planet to the
sun?
16. What would happen if a planet absorbed all the
energy it receives from the sun?
17. Explain the difference between thermal radiation
and sunlight. Is there a difference?
18. Why does most sunlight pass though Venus
atmosphere while thermal radiation is partly
absorbed?
19. What gives Mars its reddish color?
20. Mar’s atmosphere is similar in composition to
Venus (mostly CO2). Why is Mars so cold while
Venus is so hot?
Section 21.3
21. Does all life on Earth require sunlight? Give two
examples to support your answer.
22. Where do scientists believe the deepest liquid
water oceans in the solar system can be found
A NATURAL APPROACH TO CHEMISTRY
23. If a moon has no craters, what does this tell us
about its geology?
24. Research three hydrocarbon compounds that are
liquid at -180°C. Are any of these present on
Titan?
28. The inverse square law describes how the intensity
(I) of solar radiation drops off with distance from
the Sun or any other star. The luminosity (L) is the
total energy output of the star in watts and R is the
distance from from the star to the planet in meters.
L
I = ------------2
4πR
Section 21.1 Quantitative Problems
25. Write down a possible nuclear reaction that could
make magnesium in a star from lighter elements.
The rules are:
a. The total of protons + neutrons must balance
on both sides of the reaction.
b. The reaction must involve only 2.
c. A neutron can become a proton according to
the reaction n → p + ν e + e + where νe is an
electron neutrino and e+ is a positron
(antimatter).
26. The Sun has a mass of 2.0 × 1030 kg. We know
from calculated models that the Sun’s core, where
nuclear reactions occur, is about 50% of its mass,
or 1.0 × 1030 kg. From the energy output we know
that the Sun fuses 3.8 × 1028 protons per second
into helium. Calculate how long it will take the
Sun to use up 25% of the hydrogen in its core.
Express your answer in years. (Hint: The mass of
a proton is 1.67 × 10-27 kg)
Section 21.2 Quantitative problems
27. Make a graph of the surface temperatures of the
inner planets versus the distance form the Sun. Fit
a smooth curve to Mercury, Earth, and Mars. You
may ignore Venus as an anomaly for the purposes
of the graph.
a. Estimate the radius of an orbit that would
make the average surface temperature 100°C.
b. Estimate the radius of an orbit that would
make the average surface temperature 0°C.
c. This region is known as the “life zone” for
potential orbits of habitable planets. Where is
Earth in the life zone of the Sun? Is our planet
in the middle or near one or the other edge?
A NATURAL APPROACH TO CHEMISTRY
a. Calculate the intensity (w/m2) of sunlight at
the top of Earth’s atmosphere. For the Sun, L =
3.8 × 1026 watts and the distance between the
sun and Earth is 150 × 109 meters.
b. Suppose Earth were orbiting Alpha Centaurii
A, the nearest star to Earth. This star has a
luminosity of 5.7 × 1026 watts. Calculate the
intensity of light at Earth’s orbit around Alpha
Centaurii A and discuss whether water would
exist on Earth’s surface or not. Compare your
intensity to that for Venus in arriving at your
answer.
29. The power of thermal radiation increases with
temperature to the fourth power according to the
Stefan-Boltzman law . I = σT 4 where I is the total
power emitted (w), R is the area of the emitting
surface (m2), T is the temperature in K, and s is the
Stefan-Boltzman constant, s = 5.67 × 10-8 J/
s.m2.K4.
a. The surface area of the Sun is 6.18 × 1018
square meters. The temperature of teh Sun’s
surface is 5,780K. Calculate the power
radiated by the Sun.
b. Suppose the temperature of the surface of the
Sun were to increase by 5%. What change
does that make in the power radiated by the
Sun? Express your answer as a percent.
Section 21.3
30. Europa has a mass of 4.2 × 1022 kg and a radius of
1,550 kilometers.
a. Calculate the volume of Europa
b. Calculate Europa’s average density
c. Assume Europa is rock (5,500 kg/m3) and
water (1,000 kg/m3). What percentage of the
moon is rock and what percentage is water?
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