CHEM 10: Midterm Exam 1: Fall 2014
(150 points)
Name: ___________________________________
INSTRUCTIONS: On the front and back of the scantron, fill out your name and 7-digit student ID. Fill in this
information from left to right in the provided fields, and bubble in the values on the scantron. 1 point will be
deducted from your exam grade for incomplete or erroneous filling of the scantron.
Please read each question carefully. Where the question specifies “MARK ALL THAT APPLY”, you may need to
select more than one answer on the scantron.
1.
MARK ALL THAT APPLY: Which statements below are TRUE?
a. Qualitative observations involve quantifying variables with measurements backed by numbers.
b. An experiment must be reproducible to be meaningful.
c. A falsifiable hypothesis must be capable of being proven 100% correct.
d. Scientific beliefs must be testable by experiment.
e. None of the statements above are true.
2.
Convert this number to proper SCIENTIFIC scientific notation: 1,670,000
-4
a. 1.67 x 10
-6
b. 1.67 x 10
4
c. 1.67 x 10
5
d. 1.67 x 10
6
e. 1.67 x 10
3.
Convert this number to proper SCIENTIFIC notation: 0.000078
-4
a. 7.8 x 10
-5
b. 7.8 x 10
4
c. 7.8 x 10
5
d. 7.8 x 10
e. None of the above are correct.
4.
Convert this number to STANDARD notation: 120. x 10
a. 0.00012
b. 0.000012
c. 120000000
d. 12000000
e. None of the above are correct.
5.
Convert this number to STANDARD notation: 13.5 x 10
a. 13,500
b. 135,000
c. 1,350,000
d. 0.00135
e. 0.0000135
6.
The vast majority of the VOLUME of a single atom is occupied by the:
-7
a. nucleus
7.
b. electrons
c. protons
4
d. neutrons
e. It depends on whether it’s a solid, liquid or
gaseous element
The vast majority of the MASS in a single atom is accounted for in the:
a.
nucleus
b. electrons
c. charge
d. It depends on whether it’s a solid, liquid or gaseous element
8.
a.
MARK ALL THAT APPLY: Which samples below are MIXTURES of substances?
b.
9.
c.
d.
e. None of the above
What’s the difference between an atom and a molecule?
a. A molecule is made only of electrons, while an atom is made of neutrons.
b. A molecule is made only of protons, while an atoms is made of many electrons.
c. A molecule has a single nucleus, while atoms are combinations of multiple molecules bonded together.
d. An atom has a single nucleus, while molecules are combinations of multiple atoms bonded together.
e. None of the above: an atom and a molecule are the same thing, but with different numbers of neutrons.
10. At the atomic level, what is the difference between a liquid and a gas?
a. Both phases have particles that are close together, but a liquid has particles that are fixed in space and
cannot move relative to one another.
b. Both phases have randomly moving particles, but the distance between gas particles is large in comparison
to particles in a liquid.
c. A gas has particles that are close together, while a liquid has particles that are far apart.
d. A gas has particles that are fixed in space and cannot move relative to one another, and a liquid is the
opposite.
11. MARK ALL THAT APPLY: Which of the events below are chemical changes (NOT physical changes)?
a. ice melting to form liquid water
b. iron metal rusting in the presence of air and water to form iron oxide
c. liquid water boiling to form steam
d. wood burning to form carbon dioxide gas and water vapor.
e. None of the above are chemical changes. These are all physical changes.
12. MARK ALL THAT APPLY: How does neutral carbon-14 differ from neutral carbon-12?
a. Carbon-14 has more protons than carbon-12.
b. Carbon-14 has more neutrons than carbon-12.
c. Carbon-14 has more electrons than carbon-12.
d. Carbon-14 has a larger mass than carbon-12.
e. They don’t differ—all isotopes of carbon are identical.
4-
13. How many protons are in a negatively charged carbon atom with an overall charge of -4 (C )?
a. 2
b. 4
c. 6
d. 10
e. It depends on the type of carbon isotope that is being considered.
3-
14. How many neutrons are present in the nucleus of a negatively charged phosphorus atom with an overall charge of -3 (P )?
a. 12
b. 15
c. 18
d. 31
e. It depends on the type of phosphorus isotope that is being considered.
+6
15. How many total electrons are in a positively charged chromium ion with a +6 overall charge (Cr )?
a. 6
b. 18
c. 24
d. 30
e. It depends on the type of chromium isotope that is being considered.
16. For a neutral calcium atom (Ca) with a mass number of 40 (calcium-40), the number of protons, neutrons, and electrons is:
a. 20 protons, 40 neutrons, and 20 electrons.
b. 40 protons, 20 neutrons, and 20 electrons.
c. 20 protons, 20 neutrons, and 20 electrons.
d. 20 protons, 22 neutrons, and 18 electrons.
e. None of the above.
17. Which isotope of Bromine (Br) has the same number of PROTONS as Arsenic-74?
a. Bromine-33
b. Bromine-72
c. Bromine-74
d. Bromine-76
e. None of the above.
18. Which isotope of Xenon (Xe) has the same number of NEUTRONS as Cesium-130?
a. Xenon-54
b. Xenon-55
c. Xenon-129
d. Xenon-131
e. None of the above.
19. How does nuclear fusion differ from nuclear fission?
a. Fusion involves larger nuclei breaking into smaller nuclei.
b. Fission involves smaller nuclei combining into larger nuclei.
c. Fusion involves smaller nuclei combining into larger nuclei.
d. None of the above.
20. MARK ALL THAT APPLY: Which statements below are TRUE?
a. All forms of radiation are dangerous & and should be treated with caution.
b. Beta radiation can be blocked by a single sheet of paper.
c. Alpha radiation causes more damage when ingested compared to external exposure.
d. As part of the general public, most of our annual exposure to radiation is from man-made sources like
nuclear power plants & the fallout from atomic weapons.
21. Which form of radiation is MOST penetrating?
a. Alpha (α) radiation
b. Beta (β) radiation
c. Gamma (γ) radiation
d. Alpha, beta & gamma radiation are equally penetrating.
22. Elements larger than iron (Fe) are made in which process?
a. Big bang nucleosynthesis
b. Stellar nucleosynthesis
c. The triple alpha process
d. Supernova nucleosynthesis
e. None of the above.
23. Consider a radioactive sample of Americium-240. After 2 half-lives, how much original radioactive Americium will
remain?
a. With each half-life, 50% of the original sample decays, so after two half-lives, none of the Americium will
remain.
b. With each half-life, 50% of the sample decays, so after two half-lives, 25% of the Americium will remain.
c. The total amount of radioactive Americium will increase 50% after each half-life, so there will be 100% more
radioactivity present after 2 half-lives.
24. What type of particle is released in the radioactive decay below?
a.
b.
c.
d.
e.
an alpha particle:
a high energy electron:
a positron:
a gamma particle:
None of the above
25. What type of particle is released in the radioactive decay below?
a.
b.
c.
d.
e.
an alpha particle:
a high energy electron:
a positron:
a gamma particle:
None of the above
26. What type of particle is released in the radioactive decay below?
a.
b.
c.
d.
e.
an alpha particle:
a high energy electron:
a positron:
a gamma particle:
None of the above
-
27. What is the daughter isotope produced by beta minus (β ) decay of technetium-99 as shown below?
a.
b.
c.
d.
e.
Ruthenium-98
Ruthenium-99
Molybdenum-99
Molybdenum-98
Niobium-92
28. What is the daughter isotope produced by alpha decay of plutonium-240 as shown below?
a.
b.
c.
d.
e.
Curium-244
Curium-236
Uranium-92
Uranium-244
Uranium-236
29. What is the daughter isotope produced by positron emission of fluorine-18 as shown below?
a.
b.
c.
d.
e.
Oxygen-8
Oxygen-18
Neon-10
Neon-18
Neon-17
EXTRA CREDIT: (5 points) Attempt after finishing the main exam and checking your work
Uranium-236, generated by bombarding uranium-235 with neutrons, can undergo fission according to the two
reactions below. Each fission produces two daughter isotopes while releasing 3 neutrons (which can continue a
chain reaction, generating more uranium-236 from uranium-235) and tremendous amounts of energy. Sustaining
this nuclear fission can be used for atomic bombs or energy production.
For each reaction, fill in the blanks to predict the other expected daughter isotope produced.
What is the source of the energy produced in these nuclear fissions? Briefly explain your reasoning with a
mathematical equation.