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GNC501S - GENERAL CHEMISTRY 1A - 1ST OPP - JUNE 2023 |
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n Am I BI A u n IVER s ITY
OF SCIEnCE Ano TECHnOLOGY
FACULlYOF HEALTHN, ATURALRESOURCEASNDAPPLIEDSCIENCES
DEPARTMENTOF BIOLOGYC, HEMISTRYAND PHYSICS
QUALIFICATIONB:ACHELOROF SCIENCE
QUALIFICATIONCODE:07BOSC
COURSECODE:GNC501S
LEVEL5:
COURSENAME:GENERALCHEMISTRY 1A
SESSIONJ:UNE 2023
PAPERT: HEORY
DURATION3: HOURS
MARKS:100
FIRSTOPPORTUNllYEXAMINATIONQUESTIONPAPER
EXAMINER(S) MRS. LEONORITHA R. NAOMAS
MODERATOR: DR. MARIUS MUTORWA
INSTRUCTIONS
1. Answer ALL the questions.
2. Write clearly and neatly.
3. Number the answers clearly
4. All written work must be done in blue or black ink and sketches can
be done in pencil
5. No books, notes and other additional aids are allowed
PERMISSABLMEATERIALS
Non-programmable calculators
ATTACHMENTS
1. List of useful constants
2. Periodic Table
THISQUESTIONPAPERCONSISTSOF9 PAGES
(Including this front page, list of constants and periodic table)
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SECTIONA
[60]
QUESTION1: Multiple ChoiceQuestions
[60]
• There are 20 multiple choice questions in this section. Each question carries
3 marks.
• Answer ALLquestions by selecting the letter of the correct answer.
• Choose the best possible answer for each question, even if you think there is
another possible answer that is not given.
1. Which of the following pairs does not show an acid and its conjugate base?
A. HNO3 and No3-
B. H2S04and HS04-
C. H2S04and so/-
D. HS04- and so/-
2. A sample of helium gas occupies 2.65 Lat 1.20 atm. What pressure would this sample of gas
exert in a 1.50-L container at the same temperature?
A. 3.31 atm
B. 1.20 atm
C. 2.12 atm
D. 0.679 atm
3. If the temperature of an ideal gas is raised from 100°C to 200°(, while the pressure remains
constant, the volume:
A. remains the same
B. doubles
C. goes to 1/2 the original volume
D. none of these
4. Which conditions of P and Tare most ideal for a gas?
A. low P, high T
B. high P, low T
C. high P, high T
D. depends on the gas
5. Calculate the number of atoms in 54.0 g of aluminum.
A. 1.21 x 10"24 atoms Al
B. 2.11 x 10"21 atoms Al
C. 0.73 x 10"24 atoms Al
D. 1.94 x 10"24 atoms Al
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6. The compound given below is called __ .
A. butyl acetate
B. ethyl pentanoate
C. propyl pentanoate
D. ethyl butanoate
7. Which is NOT a physical property of alcohols or phenols?
A. Phenols are generally only slightly soluble in water.
B. The solubilities of normal primary alcohols in water decrease with increasing molecular
weight.
C. The hydroxyl group of an alcohol is non polar.
D. Due to hydrogen bonding, boiling points of alcohols are much higher than those of
corresponding alkanes.
8. A compound with a composition of 87.5 % N and 12.5 % H was recently discovered. What is
the empirical formula for this compound?
A. NH2
B. N2H3
C. NH
D. N2H2
9. The electronic configuration of the element whose atomic number is 26 is:
A. 1s2 2s 2p6 3s2 3p6 4s0 3d8
B. 1s2 2s2 2p6 3s2 3p6 3d6 4s2
C. 1s2 2s2 2p6 3s2 3p6 4s2 3d6
D. 1s2 2s2 2p6 3s2 3p6 4s2 3d4 4p2
10. Consider a 3dxz orbital. Which of the following statements is incorrect?
A. The xz plane is a nodal surface.
B. The xz plane divides the electron probability distribution into two identical mirror-image
halves.
C. The xy plane divides the electron probability distribution into two identical mirror-image
halves.
D. The yz plane divides the electron probability distribution into two identical mirror-image
halves.
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11. Which of the following has the largest radius?
A. F
8. N
C. C
D. 0
12. What is the mass of one mole of acetylsalicylic acid (aspirin}, C9Hs04?
A. 29 g
8. 196 g
C. 180 g
D. none of the above
13. Which of the following combinations of names and formulas is incorrect?
A. H3 P04 phosphoric acid
8. HN03 nitric acid
C. NaHC03 sodium carbonate
D. H2C03carbonic acid
14. What is the name of Nal?
A. sodium iodide
8. sodium(I} iodide
C. sodium monoiodide
D. sodious iodide
15. The freezing point of pure camphor is 178.4 °C, and its molal freezing-point constant,
Kf is 40.0 °C/m. Find the freezing point of a solution containing 3.00 g of a compound of
molar mass 125 g/mol in 45.0 g of camphor.
A. 174.1 °C
8. 157.1 °C
C. 135.2 °C
D. 140.4 °C
16. Which of the following is a correct description of the natural direction of a 8r<Z)nsted-Lowry
acid-base reaction?
A. weaker acid + weaker base stronger acid + stronger base
8. weaker acid + stronger base stronger acid+ weaker base
C. stronger acid + weaker base weaker acid + stronger base
D. stronger acid + stronger base weaker acid + weaker base
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17. A molecule with the formula (3Hs is a(n}:
A. hexane
B. propane
C. decane
D. butane
18. The general formula for noncyclic alkenes is:
A. CnH2n
B. CnHn
C. CnH2n+2
D. CnH2n-2
19. Standard conditions (STP) are:
A. 0°C and 2 atm
B. 32°F and 76 torr
C. 273 Kand 760 mmHg
D. 4°C and 7.6 mmHg
20. An object has a volume of 0.090 m3. Its volume given in cm3 is
A. 0.90
B. 90 000
C. 9000
D. 900
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SECTIONB:
[40]
There are FOUR questions in this section. Answer all questions. Show clearly, where necessary,
how you arrive at the answer as all working will carry marks.
Question1
[15)
1.1 A particular sample of vinegar has a pH of 2.90. If acetic acid is the only acid that vinegar contains
Ka= 1.8 x 10-si, calculate the concentration of acetic acid in the vinegar.
(5)
1.2 A reaction requires a 500 ml solution with a pH of 2.5. What would be the mass of H2SO4
required to make up such solution?
(5)
1.3 A 0.1044-g sample of an unknown monoprotic acid requires 22.10 ml of 0.0500 M NaOH to
reach the end point. What is the molecular weight of the unknown?
(5)
Question2
[7)
2.1 Given the equation
2KCIO3(s) 2KCl(s) + 3O2(g)
A 3.00-g sample of KCIO3is decomposed and the oxygen at 24.0°C and 0.982 atm is
collected. What volume of oxygen gas will be collected assuming 100% yield?
(4)
2.2 A balloon has a volume of 1.20 lat 24.0°C. The balloon is heated to 48.0°C. Calculate the
new volume of the balloon.
(3)
Question3
[9]
An aqueous solution is prepared by diluting 3.30 ml acetone (d = 0.789 g/ml) with water to a final
volume of 75.0 ml. The density of the solution is 0.993 g/ml. What is the molarity, molality and mole
fraction of acetone in this solution?
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Question4
[9]
Give the IUPAC names for the following compounds:
4.1 Identify the class of the following compounds. For any alkanes, alkenes, alkynes,
aromatic compounds, carboxylic acids or alcohols, provide the IUPACname of the molecule.
(6)
(i}
(ii}
0
0
(iii}
~OH
4.2 Draw the structural formulas for the following compounds:
(3)
a) 1-pentene
b) 4-methylhexanoic acid
c) 2-methyl-3-heptyne
THE END
GOODLUCK
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USEFULCONSTANTS:
Gas constant, R = 8.3145 J ·mo1-1. K-1 = 0.083145 dm 3 ·bar· mo1-1. K-1 = 0.08206 L atm mo1-1.K-1
1 Pa· m3 = 1 kPa.L = 1 N · m = 1 J
1 atm = 101 325 Pa= 760 mm Hg= 760 torr
Avogadro's Number, NA= 6.022 x 1023 mo1-1
Planck's constant, h = 6.626 x 10-34 Js
Speed of light, c = 2.998 x 108 ms-1
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PERIODIC TABLE OF THE ELEMENTS
18
1
2
H
1.00794
2
13
14
15
He
16
17 4.00260
34
56
7
8 9 IO
Li Be
B C N 0 F Ne
6.941 9.01218
10.81 12.01 l 14.0067 15.9994 18.9984 20.179
11 12
Na Mg
13 14 15
Al Si p
16 17 18
s Cl Ar
22.9898 24.305 3
4
5
6
7
8
9
10
11
12 26.9815 28.0855 30.9738 32.06 35.453 39.948
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
39.0983 40.08 44.9559 47.88 50.9415 51.996 54.9380 55.847 58.9332 58.69 63.546 6538 69.72 72.59 74.9216 78.96 79.904 83.8
37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
"'Cl
Rb Sr y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cl)
(l'Q
Ill
U)
85.4678 87.62 88.9059 91.22 92.9064 95.94 {98) 101.07 102.906 106.42 107.868 112.41 114.82 118.69 121.75 127.6 126.9 131.29
55 56 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
0......
U)
Cs Ba Lu Hf Ta w Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
132.905 137.33 174.967 178.49 180.948 183.85 186207 190.2 19222 195.08 196.967 200.59 204383 2072 208.908 {209) (210) (222)
87 88 103 104 105 106 107 108 109 110 111 112
114
116
118
Fr Ra Lr Rf Db Sg Bh Hs Mt Uun Uuu Uub
Uuq
(223) 226.02S (260) (261) (262) (263) (264) (265) 268) (269) (272) (269)
Uuh
Uuo
Lantbanides:
57 58 59 60
La Ce Pr Nd
138.906 140.12 140.908 14424
61 62 63 64 65 66 67 68 69 70
Pm Sm Eu Gd Tb Dy Ho Er Tm Yb
(145) 15036 151.96 157.25 158.925 162.50 161.930 167.26 166.934 173.04
Actinides:
89 90 91 92 93 94 95 96 97 98 99 100 101 102
Ac Th Pa u Np Pu Am Cm Bk Cf Es Fm Md No
227.028 232.038 231.036 238.029 237.048 (244) (243) (247) (247) (251) (252) (257) (258) (259)