CHEM 1405 PRACTICE EXAM I (Ch. 1 – 2) 2 nd edition of Blei and Odian
Multiple Choice: Choose the best (one) answer. Show in bold.
1.
Which of the following is/are physical properties?
(A) Density & color
(B) Conductivity & melting (i.e. freezing) point
(C) Condensation & vaporization
(D) Odor & magnetism
(E) All of the above.
Note: Concept is from page 5 of the textbook.
Definition: Physical properties are the ones you can get them back by changing the temperature or pressure. The procedure used by adapting physical properties is called the physical process.
Chemical properties are the ones you cannot get them back.
2.
Which of the following statement is true?
(A) A compound is formed by different elements.
(B) An element is a mixture.
(C) An element can contain two or more pure substances.
(D) Boiling an egg is a physical process.
(E) Compression of a gas is a chemical process.
Note: p. 4, p. 5, & p. 7.
Definition: Pure substances can be either any of the following: atoms, elements, molecules or compounds, which cannot be separated by changing the physical properties.
A mixture contains two or more pure substances, which can be separated by usually filtration or evaporation.
3.
Which of the following material is a mixture?
(A) Wood
(B) Baking soda
(C) Sodium atom
(D) Table salt
(E) Hydrogen gas
Note: p. 5.
Concept: When presented by chemical formulas, mixture (like sugar water as H
2
O + C
6
H
12
O
6
) usually contains at least one plus sign and the pure substance does not (like baking soda as
Na
2
CO
3
).
4. Which of the following chemical symbols is correctly matched?
(A) Tin, Ti
(B) Sodium, So
(C) Mercury, Hg
(D) Potassium, P
(E) Lead, Le
Note: p. 8 Table 1.1, check with periodic table and memorize them.
5.
Which of the following statement is wrong concerning the significant figures?
(A) There are five significant figures in 53.410.
(B) There are three significant figures in 0.00405.
(C) The sum of 202.450 and 16.25 written in scientific notation and giving the correct number of significant figures is 2.1870 x 10 2 .
(D) The result of multiplying 25.20 x 10
–2
and 1.167 x 10 -4 written in scientific notation and giving the correct number of significant figures is 2.941 x 10 -5 .
(E) None of the above.
Note: p.p. 11-12 & 15-17. You need to memorize all the rules concerning the significant figures and the rules related to addition or subtraction and multiplication or division. Many students do
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not know the differences between addition/subtraction and multiplication/division. See two examples below:
Remember that the answers obtained from calculators are always WRONG when considering the significant figures.
Ex. 202.450 + 16.25 = 218.700 from calculator, which must be corrected with the least decimal points of the components, and thus it is 218.70, and thus it must be written in scientific notation and giving the correct number of significant figures as 2.1870 x 10 2 .
Ex. (25.20 x 10
–2
) x (1.167 x 10 -4 ) = 2.94084 x 10
–5
from calculator, of which must be corrected with the lease digit of the significant figures, and thus it must be written in scientific notation and giving the correct number of significant figures as 2.941 x 10
–5
.
6.
How many significant figures does the number 101000 contain?
(A) Three
(B) Four
(C) Five
(D) Six
(E) All of the above
Note: p.p. 11-12. See Q 5.
7.
Which of the following expressions is correct scientific notation for the measurement 225.2 cm?
(A) 225.2 x 10 0
(B) 22.52 x 10 1
(C) 2.252 x 10 2
(D) 0.2252 x 10 3
(E) All of the above
Note: p.p. 12-14.
Scientific notation can only have one digit in front of a decimal point. When the decimal point moves to the left side, the exponent becomes more positive, when it moves to the right, the exponent becomes more negative.
8.
Which of the following expression is not equivalent to 5.152 x 10
– 4
?
(A) 0.0005152 x 10 0
(B) 0.005152 x 10 -1
(C) 0.05152 x 10 -2
(D) 0.5152 x 10 -3
(E) None of the above
Note: p.p. 12-14. See Q7.
9.
Which of the following expression is correct for the result of multiplying 25.20 x 10
–2
and
1.167 x 10 -4 , written in scientific notation and giving the correct number of significant figures?
(A) 0.2941 x 10 -6
(B) 0.02941x 10 -5
(C) 0.002941 x 10 -4
(D) 2.941x 10 -6
(E) 2.941x 10 -5
Note: p. 15, example 1.4. Also see Q 5.
10.
Which of the following is correct concerning reporting the sum of 202.450 and 16.25 to proper significant figures and is written in scientific notation?
(A) 2.19 x 10 2
(B) 2.187 x 10 2
(C) 2.1870 x 10 2
(D) 21.87 x 10 2
(E) 218.70 x 10 2
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Note: p. 14 example 1.3. Also see Q 5.
11.
What is the volume for a substance with density of 2.5 g/cm 3 and mass of 0.5 kg?
(A) 0.2 cm 3
(B) 2.0 cm 3
(C) 20.0 cm 3
(D) 200.0 cm 3
(E) 5.0 cm 3
Note: p. 22 example 1.14.
Memorize the formula: density (g/cm 3 ) = mass (g) / volume (cm 3 ). Note that 1 kg = 1000 g.
12.
Which of the following is equivalent to 230 o C?
(A) 503 K
(B) + 43 K
(C) - 43 K
(D) 300 K
(E) 20 K
Note: p. 25. Memorize the formula: K = 273.15 + o C and then see which choice is closer to the answer calculated.
13.
Which of the following is equivalent to 503 K?
(A) 937.4 o F
(B) 247.4 o F
(C) 446 o F
(D) 300 o F
(E) 230 o F
Note: p. 26 example & problem 1.17. Memorize the formula: o F = 1.8 x o C + 32. Note that there is no direct conversion between the K and o F. So in this question, you must convert K to o C first and then convert o C to o F.
14.
How much energy is removed when a 350 g can of soda is placed in a refrigerator and cooled from
30 o C to 15 o C. Assume the specific heat of soda is identical with that of water, 4.184 J/go C.
(A) 21.97 kJ
(B) 37.45 kJ
(C) 247.4 kJ
(D) 44 kJ
(E) 365 kJ
Note: p. 29 example & problem 1.19.
Memorize the formula: energy (q) = specific heat (s) x mass (g) x temperature change.
Note that temperature change = final temperature – initial temperature
15.
What is the final temperature for a 300 g of olive oil (specific heat is 1.97 J/go C) heated with 10 kJ of heat. Assuming that the starting temperature of the oil was 4 o C and no heat is lost to the surroundings?
(A) 16.92 o C
(B) 24.4 o C
(C) 4.47 o C
(D) 36.5 o C
(E) 20.92
o C
Note: p. 29 example & problem 1.18 & 1.19. See Q14. Note that 1 kJ = 1000 J.
16.
What is the atomic number?
(A) Neutrons in an atom.
(B) Volume unit in an atom.
(C) Protons in an atom.
(D) amu units in an atom.
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(E) Protons plus neutrons in an atom.
Note: p. 40. This is the definition.
17.
Which of the following statement is true?
(A) Mass number is same as the average atomic mass.
(B) The sum of electrons and protons is called the mass number for an atom.
(C) Atomic mass is roughtly equal to the masses of protons plus neutrons in an atom.
(D) Atomic mass is number of atoms in a mole.
Note: p.p. 39-42. This is the definition.
18.
How many protons are there in an element with 30 neutrons, 21 electrons and a charge of 4+?
(A) 25
(B) 37
(C) 21
(D) 17
(E) 55
Note: p.p. 39-42 example & problem 2.3 & 2.4.
Positive charge indicates there are more protons than electrons; while the negative charge indicates there are more electrons than protons. This is because neutron does not carry charge, a proton carries one positive charge, and an electron carries one negative charge.
19.
How many protons are there in an element with 28 neutrons, 24 electrons and a charge of 3-?
(A) 25
(B) 37
(C) 21
(D) 17
(E) 55
Note: p.p. 39-42 example & problem 2.3 & 2.4. Also see Q18.
20. Which of the following is the cause of producing isotope of an element?
(A) Electrons
(B) Protons
(C) Neutrons
(D) Both electrons and protons.
(E) Protons, neutrons, and electrons.
Note: p. 41. This is the definition. Example & problem 2.7.
21. Assuming that there are only two naturally occurring isotopes for silver: 107 Ag (amu 106.91) and
109 Ag (amu 108.90). The mass percentage of the former is 51.840% and the latter 48.16%, respectively. What is the atomic mass of this mixture?
(A) 107.87 amu
(B) 374.55 amu
(C) 207.43 amu
(D) 44.69 amu
(E) 122.12 amu
Note: p. 42 example & problem 2.8. This is a very important question and you must convert the % into decimals first and then apply the formula and memorize it:
M = M
1
X
1
+ M
2
X
2
= 106.91x0.51840 + 108.90x0.4816 = 107.87
22. Which of the following statements is true?
(A) Au, nonmetal
(B) Sb, metalloid
(C) Al, nonmetal
(D) Ar, ion
(E) Na + , atom
Note: p. 45 & Fig. 2.3 (p. 43), check with periodic table. This is the definition.
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23. Which of the following statements is true?
(A) Most of the metals are located at the far right side of the periodic table.
(B) Most of the nonmetals are located at the far left side of the periodic table.
(C) B, Si, Ge, As, Sb, Te, Po and At are metalloids.
(D) H, Li, Na, K, Rb, Cs and Fr are alkali metals.
(E) He, Ne, Ar, Kr, Xe and Rn are halogens.
Note: p.p. 42-46, check with periodic table. This is the definition.
24. Which of the following statements is/are true?
(A) That an atom is in its ground state indicates the atom is in a high-energy state.
(B) That an atom is in its ground state indicates the atom is in a medium-energy state.
(C) That an atom is in its ground state indicates the atom is in its lowest energy state.
(D) There are two or more ground states in an atom.
(E) There is only one excited state in an atom.
Note: p. 50. This is the definition.
25. Which of the following is a correct order of the subshells?
(A) p, d, s, f
(B) s, p, d, f
(C) f, d, p, s
(D) f, s, d, p
(E) s, d, f, p
Note: p.p. 51-52, Table 2.7 & Fig. 2.13 (p. 54). This is the definition.
26. Which of the following statements is true concerning the Hund’s spin-pair rule?
(A) In a shbshell with more than one orbital, the electrons will not spin-pair until every orbital in the subshell contains at least one electron.
(B) In a shbshell with more than one orbital, the electrons will spin-pair until every orbital in the subshell contains at least one electron.
(C) In a shbshell with one orbital only, the electrons will not spin-pair until every orbital in the subshell contains at least one electron.
(D) In a shbshell with one orbital only, the electrons will spin-pair until every orbital in the subshell contains at least one electron.
(E) All of the above.
Note: p. 53. This is the definition.
27. Which of the following statements is true concerning Pauli’s Exclusion Principle?
(A) Each orbital contains a minimum of two electrons that can only coexist if they are spin-paired.
(B) Each orbital contains a maximum of two electrons that can only coexist if they are spinpaired.
(C) Each orbital contains a minimum of two electrons that can only coexist if they are not spinpaired.
(D) Each orbital contains a maximum of two electrons that can only coexist if they are not spinpaired.
(E) All of the above.
Note: p. 53. This is the definition.
28. How many electrons can occupy the 4d shell?
(A) Two
(B) Four
(C) Six
(D) Eight
(E) Ten
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Note: p. 52 Table 2.7. This is an important question. Definition: there is only one s orbital, three p orbitals, five d orbitals, and seven f orbitals. Each orbital contains two electrons. Thus, two electrons can occupy s orbital, 6 for p, 10 for d, and 14 for f orbitals.
29. Which of the following is correct electron configuration for silicon (atomic number 14)?
(A) 1s 2 2s 2 2p 6 3s 2 3p 2
(B) 1s 2 2s 2 2p 6 3s 2 3p 6 3d 6 4s 2 4p 5
(C) 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 5 (arranged according to the order of principle quantum number) or 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 (arranged according to the order of orbital energy)
(D) 1s 2 2s 2 2p 6 3s 2 3p 6 3d 6 4s 2 4p 1 (arranged according to the order of principle quantum number) or 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 6 4p 1 (arranged according to the order of principle quantum number)
(E) 1s 2 2s 2 2p 6 3s 2 3p 6
Note: p.p. 54-57 & Table 2.8, 2.9 and 2.10. This is a very important question . Follow the
2s
3s
4s definition and energy order of orbital in the book. Electrons fill in order is from the upper right corner to left bottom corner starting the first row and follow the same procedure for the second, third, etc. rows.
1s
2p
3p
4p
3d
4d 4f
30. Which of the following is the element in period 4 that would form an ion by losing two electrons?
(A) Mg
(B) Al
(C) S
(D) P
(E) Ca
Note: p.p. 65-70 example & problem 3.1. This is the definition and is very important .
According to periodic table, metals lose electrons, while nonmetals gain electrons. The elements in the first column lose one electron, the second column elements lose two electrons, and the third column elements lose three electrons. The elements in the fifth column gain three electrons, the sixth column elements gain two electrons, and the seventh column elements gain one electron.
31. Which of the following is the element in period 3 that would form an ion by gaining two electrons?
(A) Mg
(B) Al
(C) S
(D) P
(E) Ca
Note: p.p. 65-70. See Q30.
32.
How many bond are needed for Group IV elements to form an octet?
(A) One
(B) Two
(C) Three
(D) Four
(E) Five
Note: p.p. 60-62. This is the definition and is very important . According to periodic table, each element in Group IV needs four bonds to form an octet, each element in Group V needs three bonds to form an octet, each element in Group VI needs two bonds to form an octet, and each element in Group VII needs one bond to form an octet.
33.
Analysis of 5.150 g of ethanol (ethyl alcohol) yields 2.685 g of carbon, 0.6759 g of hydrogen, and
1.789 g of oxygen. Calculate the mass percent (%) of carbon element in the compound.
(A) 52.136
(B) 13.124
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(C) 34.734
(D) 40.951
(E) 4.520
Note: p. 42 & example 2.8. This is the definition and is very important . Memorize the formula:
% element = 100 x {mass (g) of element/total mass (g)}
= 100 x {2.685/(2.685+0.6759+1.789)} = 52.136
Note since ethanol contains carbon, hydrogen and oxygen and thus the total mass is the sum of the masses from these three components.
34.
What are the sign and magnitude of the charge of an atom containing 24 protons, 23 neutrons, and
22 electrons?
(A) +2
(B) +1
(C) 0
(D) -1
(E) -2
Note: p. 40 & examples 2.3 & 2.4. Also Q18 and Q19.
35.
Which of the following is correct concerning reporting the subtraction of 3.965 from 4.8 to proper significant figures?
(A) 0.835
(B) 0.83
(C) 0.84
(D) 0.8
(E) None of the above
Note: p. 17 example 1.8. Also Q5.
36. Which of the following expression is correct for the result of division between 5.892 and
6.10, giving the correct number of significant figures?
(A) 0.96590
(B) 0.9659
(C) 0.965
(D) 0.966
(E) None of the above
Note: p. 15, example 1.5. Also see Q5.
37.
A 55.9kg person displaces 57.2 L of water when submerged in a water tank. What is the density of the person in g/cm 3 ?
(A) 29.8
(B) 9.77
(C) 0.94
(D) 0.98
(E) 8.74
Note: p. 20 unit conversion & p. 22 example 1.14 (density) example 1.14. Also see Q11.
38.
Which of the following is a chemical change?
(A) The fading of a carpet upon repeated exposure to sunlight.
(B) The evaporation of fingernail-polish remover (acetone) from the skin.
(C) The shiny appearance of silver.
(D) The ability of dry ice to vaporize without melting.
(E) The low mass (for a given volume) of aluminum relative to other metals.
Note: Concept is from page 5 of the textbook. Chemical change is the change that you can not get it back to original. Or say, chemical change is a process using chemical property. Also see Q1 and
Q2.
39.
Which element is described by the electron configuration of [Ar]4s 2 ?
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(A) Be
(B) Mg
(C) Ca
(D) Sr
(E) Ba
Note: p.p. 57-60 example 2.13. This is the definition and is also very important . Memorize the following facts: According to the electron configuration, the symbol of ns 1 means Group IA, ns 2 means Group IIA, ns 2 np 1 means Group IIIA, ns 2 np 2 or ns 1 np 3 means Group IVA, ns 2 np 3 means
Group VA, ns 2 np 4 means Group VIA, ns 2 np 5 means Group VIIA, and ns 2 np 6 means Group VIIIA, where n means row number. So 4s 2 means the element is located in row number 4 and second column. The element at the intersection is Ca.
Also note that the sum of all electrons from superscripts and the ones in the [ ] indicate the atomic number. Here, the symbol [Ar]4s 2 indicates that [Ar] has 18 electrons plus 2 electrons as a superscript; total is 20. So the atomic number 2o is the element Ca.
40.
What positively charged ion (cation) is represented by the following electron configuration?
1s 2 2s 2 2p 6
(A) Ne
(B) Na
+
(C) F
-
(D) K
+
(E) O
-
Note: p.p. 60-61. The sum of all superscripts is 2+2+6=10 electrons but the question wants the one with positive charge. So (B) has 11 – (+1) = 10 electrons; while (D) has 19 – (+1) = 18 electrons.
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