DATE: ___________ NAME:_________________________________________ CLASS:_______
Unit 2 Test
Goal: Test your understanding of Unit 2, Chemical Reactions and Radioactivity.
Circle the letter of the best answer for each question.
1. Which of the following are responsible for chemical bonding?
A. electrons
B. neutrons
C. nuclei
D. protons
2. In which of the following do covalent bonds hold the atoms together?
A. gold
B. magnesium chloride
C. carbon dioxide
D. aluminum oxide
3. Consider the following unbalanced chemical equation:
Na + O2 Æ Na2O
What is the coefficient in front of Na in the balanced equation?
A. 1
B. 2
C. 3
D. 4
4. Which of the following is a base?
A. NaF
B. KOH
C. HCl
D. KNO3
5. Which of the following could be the product of a neutralization reaction between NaOH and
HCl?
A. NaH
B. NaCl
C. O2
D. ClOH
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6. Which element must always be present in an organic compound?
A. hydrogen
B. oxygen
C. carbon
D. iron
7. Which type of chemical reaction will occur between potassium and chlorine?
A. synthesis
B. decomposition
C. single replacement
D combustion
8. Which of the following will decrease the rate of a chemical reaction?
A. adding a catalyst
B. grinding a chunk of reacting solid into smaller pieces
C. lowering the temperature
D. raising the temperature
9. Consider the following equation:
What type of nuclear decay is this?
A. alpha
B. beta
C. gamma
D. fission
10. A 24 g sample of a radioactive isotope decayed to 3 g in 4 minutes. How many half lives
have passed during this time?
A. 1
B. 2
C. 3
D. 4
More questions…
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Match the Term on the left with the best Descriptor on the right.
____
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____
____
____
____
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____
____
Term
11. valence electrons
12. ionic bond
13. binary covalent compound
14. reactants
15. pH scale
16. hydrocarbon
17. combustion
18. catalyst
19. radioactive decay
20. fusion
Descriptor
A. produces carbon dioxide and water
B. substances which are used up in a reaction
C. formed by the attraction of oppositely charged ions
D. involves the breaking apart of a nucleus into two
smaller ones
E. a compound that contains water and carbon
F. contains two non-metals
G. speeds up a reaction without being consumed
H. a process in which unstable nuclei lose energy by
emitting radiation
I. involves the combining of small nuclei to make a
larger one
J. electrons in the outermost shell of an atom or ion
K. a kind of organic compound
L. refers to how much solute is dissolved in a solution
M. indicates how acidic or basic a solution is
21. Consider the following diagram, which shows a compound composed of an atom of
hydrogen bonded to an atom of fluorine.
(a) What type of chemical bond is illustrated by this diagram?
__________________________________________________________________________
(b) Explain how this kind of bond forms.
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
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22. The following diagram related to the element iron is taken from the periodic table.
(a) What is the average atomic mass of iron?
__________________________________________________________________________
(b) How many protons are in the nucleus of an atom of iron?
__________________________________________________________________________
(c) How many electrons are in an iron(III) ion?
__________________________________________________________________________
23. Write the names of the following ionic compounds.
(a) NaBr
__________________________________________________________________________
(b) FeF2
__________________________________________________________________________
(c) (NH4)3PO4
__________________________________________________________________________
More questions…
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24. Write the names of the following covalent compounds.
(a) N2S3
__________________________________________________________________________
(b) PCl5
__________________________________________________________________________
(c) XeF6
__________________________________________________________________________
25. Balance the following equations.
(a) Sn + O2 Æ
SnO
__________________________________________________________________________
(b) Li + H2O Æ LiOH + H2
__________________________________________________________________________
(c) C3H8 + O2 Æ CO2 + H2O
__________________________________________________________________________
26. (a) What is an acid-base indicator?
__________________________________________________________________________
(b) What is the colour of a solution of baking soda in methyl orange indicator?
__________________________________________________________________________
(c) Phenolphthalein indicator is added to a colourless solution. The solution turns pink after the
indicator has been added. What can you conclude about the pH of the solution?
__________________________________________________________________________
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27. The organic compound called propane is used as a camp fuel. Propane is represented below
in a ball and stick diagram.
Different amounts of shading indicate that two elements are present in this compound. The
lighter shaded spheres represent the element hydrogen.
(a) What element is represented by the dark shaded spheres?
__________________________________________________________________________
(b) Write the molecular formula for propane.
__________________________________________________________________________
(c) Write the structural formula for propane.
__________________________________________________________________________
More questions…
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28. For each chemical reaction listed below, do the following:
(i) Classify the type of reaction as a synthesis, decomposition, single replacement, double
replacement, acid-base neutralization, or combustion reaction.
(ii) Complete the equation by predicting the products and balance the equation.
(a) Na + Cl2 Æ
(i) Type of reaction: __________________________________________
(ii) Balanced equation: _____________________________________________________
(b) HCl + NaOH Æ
(i) Type of reaction: __________________________________________
(ii) Balanced equation: _____________________________________________________
(c) CuCl2 + Al Æ
(i) Type of reaction: __________________________________________
(ii) Balanced equation: _____________________________________________________
29. The following diagram illustrates a common type of radioactive decay:
(a) What type of decay is represented in the diagram?
__________________________________________________________________________
(b) Why does this kind of radioactive decay cause one element to turn into another element?
__________________________________________________________________________
__________________________________________________________________________
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30. Consider the following graph showing the decay curve for uranium-235.
(a) How long is one half-life of uranium-235?
__________________________________________________________________________
(b) What percentage of uranium-235 remains after 2000 million years?
__________________________________________________________________________
(c) How much time passes before only 10% of the original sample of uranium-235 remains?
__________________________________________________________________________
— END —
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ANSWER KEY
Unit 2 Test
Chemical Reactions and Radioactivity
1. A
2. C
3. D
4. B
5. B
6. C
7. A
8. C
9. B
10. C
11. J
12. C
13. F
14. B
15. M
16. K
17. A
18. G
19. H
20. I
21. (a) covalent
(b) The atoms combine by sharing electrons in such a way that both atoms attain a complete
outer shell.
22. (a) 55.8
(b) 26
(c) 23
23. (a) sodium bromide
(b) iron(II) fluoride
(c) ammonium phosphate
24. (a) dinitrogen trisulfide
(b) phosphorus pentachloride
(c) xenon hexafluoride
25. (a) 2Sn + O2 Æ 2SnO
(b) 2Li + 2H2O Æ 2LiOH + H2
(c) C3H8 + 5O2 Æ 3CO2 + 4H2O
26. (a) An acid-base indicator is a pigment that has different colours depending on the acidic or
basic nature of a solution that it is placed in.
(b) yellow
(c) The pH is greater than about pH 8.
27. (a) carbon
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(b) C3H8
(c) CH3CH2CH3 (abbreviated form) or can also be drawn out.
28.
(a)
(i) synthesis
(ii) 2Na + Cl2 Æ 2NaCl
(b)
(i) acid-base neutralization
(ii) HCl + NaOH Æ NaCl + H2O (balanced)
(c)
(i) single replacement
(ii) 3CuCl2 + 2Al Æ 2AlCl3 + 3Cu
29. (a) alpha
(b) The alpha particle, which is a helium nucleus, contains two protons. This means that when Ra
emits an alpha particle, the number of protons in its nucleus decreases by two. Changing the
number of protons in a nucleus changes the identity of the element.
30. (a) about 700 million years
(b) about 14%
(c) about 2300 million years
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