Houston Community College System
Chemistry 1405
Final Sample Exam
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CHEM 1405
Final Exam (Chap. 1- 13)
Name:_____________________
Score:
PART I – Multiple choice (2 points each)
DIRECTION- Please write your correct choice in the space provided.
-------1. Which of the following is a basic step in the scientific method?
A) Perform an experiment and collect data
B) Analyze experimental data and propose a hypothesis
C) Test a hypothesis and state a theory or law
D) All of the above.
-------2. Round off the following measurement to the three significant digits: 107.500g
A)107g
B)108g
C)107.0g
D)107.4
-------3. Add 7.77g to 51.665g and round off the sum to the proper significant digits
A)59.0g
B)59.4g
C)59.43g
D)59.44g
-------4. Express 0.000000000000000000000000000000010 as an exponential number.
A) 1.0 x 10-10
B) 1.0 x 10-32
C) 1.0 x 10 -33
D) 1.0 x 1032
-------5. Which of the following is not a branch of chemistry?
A) Analytical Chemistry
B) Environmental Chemistry
C) Physical Chemistry
D) Biological chemistry
-------6. Which of the following unit factors is derived from: 1 mile = 1760 yards?
A) 1 mile/ 1 yard
B) 1760 miles/ 1 yard
C) 1760 yards/ 1 mile
D) 1760 yard/ 1760 miles
-------7. The radius of tin atom is 1.41 x 10-8 cm. What is the radius of the atom in nanometers?
1m = 10 9nm, 1m = 102 cm
A) 1.41 x 10-16 nm
B) 1.41 x 10-10 nm
C) 1.41 x 10-4 nm
D) 1.41 x 10-1 nm
-------8. A glass cylinder contains four separate liquid layers: mercury (d=13.6g/mL),
chloroform (d = 1.49g/mL), acetic acid (d= 1.05g/mL), ether (d = 0.708g/mL). If a
marble (d= 3.05g/mL) is added to the cylinder, where does it come to rest?
A) On top of the mercury layer
B) On top of chloroform layer
C) On top of acetic acid layer
D) On the top of ether layer
------9. A 50.0g sample of solid aluminum releases 420.0 calories when cooled from 100.00C to
60.00C. What is the specific heat of the metal?
A) 0.168 cal/(g x 0C)
B) 0.210 cal/(g x 0C)
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C) 0.840 cal/(g x C)
D) 4.76 cal/(g x 0C)
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-------10. Given that methanol freezes at -940C, what is the freezing point temperature on the
Kelvin scale?
A) -367K. B) -179K
C) -94K
D) 179K
-------11. Which of the following elements is an example of a semimetal?
A) H
B) C
C) Fe
D) Ge
-------12. Use the periodic table and predict which of the following elements a liquid at 250C is?
A) B
B) Ba
C) Be
D) Br
-------13. How many neutrons are in the nucleus of one atom of oxygen-18?
A) 2
B) 8
C) 10
D) 18
-------14. What is the maximum number of electrons that can occupy a 4d sublevel?
A) 4
B) 4
C) 7
D) 10
-------15. The original periodic law was based on which of the following?
A) Increasing atomic mass
B) Increasing atomic number
C) Increasing isotopic number
D) Increasing mass number.
-------16. Predict the boiling point for argon given the boiling points of Krypton (-1520C) and
Xenon (-1070C)
A) -1970C
B) -1300C
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C) -62 C
D) -450C
-------17. What is the core electron configuration for a titanium (II) ion, Ti2+?
A) (Ar)
B) (Ar) 4s2.
C) (Ar) 3d2.
D) (Ar) 4s2 3d2.
-------18. Aqueous HBr is classified as which of the following?
A) Binary ionic
B) Ternary ionic
C) Binary molecular
D) Binary acid.
-------19. What is the formula for the ionic compound composed of bismuth ion, Bi3+ , and
CN- ?
A) BiCN
B) BiCN3
C) Bi3CN
D) Bi(CN)3.
-------20. Which of the following is not evidence for a chemical reaction producing a gas?
A) An odor is detected
B) a color change is observed
C) a flaming splint is extinguished D) a burning splint bursts into flames
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------21. What are the products from the following decomposition reaction?
Co2(CO3)3(s) →
A) Co and CO2
B) CoO and CO2
C) Co2O3 and CO2
D) CoO, H2O, and CO2
-------22. How many methane molecules, CH4, have a mass of 3.2g?
A) 1.20 x 1023 molecules
B) 1.20 x 1024 molecules
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C) 1.93 x 10 molecules
D) 3.01 x 1023 molecules
-------23. If 1.00mol of krypton gas exerts a pressure of 1.00 atm at 1000C, what is the volume
of the gas? (R = 0.0821atm.L/mol.K)
A) 2.20mL
B) 8.21 L
C) 12.2L
D) 30.6L
-------24. How many valence electrons are in a bromine atom and a bromide ion?
A) 1 and 7, respectively
B) 1 and 8, respectively
C) 7 and 8, respectively
D) 7 and 10, respectively.
-------25. Which of the following ions has the following electron configuration: 1s2 2s2 2p6 3s2
3p6 4s2 3d10 4p6?
A) IB) S2C) K+
D) Sr2+
-------26. If the electronegativity values for H, N, O, and P are 2.1, 3.0, 3.5, and 2.1,
respectively, which of the following is a nonpolar covalent molecule?
A) water, H2O
B)Laughing gas, N2O
C) phosphine, PH3
D) ammonia, NH3.
-------27. What is the strongest intermolecular force in a liquid containing polar molecule?
A) Covalent bond
B) Ionic bond
C) Permanent dipole forces
D) Temporary dipole forces
-------28. What are the products from the complete combustion of a hydrocarbon?
A) Carbon dioxide and water
B) Carbon monoxide and hydrogen
C) Carbon monoxide and water
D) Carbon dioxide and hydrogen
-------29. What is the systematic name for for Ca(NO3) 2.4H2O
A) Calcium nitrate dihydrate
B) Calcium nitrate tetrahydrate
C) Calcium nitrite dihydrate
D) Calcium nitrite tetrahydrate
-------30. What is the strongest intermolecular force in a liquid having molecules with H-N
bonds?
A) Dipole forces
B) Dispersion forces
C) Hydrogen bond
D) covalent Bond
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PART II – Show your work (8 points for each question)
1. Perform the following metric-metric conversions.
a) 125 Gm to Mm
b) 255 mg to cg
c) 1.85 mL to µL
d) 8.15 x 104 Gs to ns
2a. A sample of fluorine gas occupies 855 mL at 710 mm Hg and 1550C. What is the mass of
the sample?
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b. A sample of krypton gas has a volume of 500.0mL at 225mm Hg and -1250C. Calculate the
pressure in mm Hg if the gas occupies 220.0 ml at 1000C
3a. Calculate the heat required to convert 10.0g of ice at -10.0oC to liquid water at 20.00C. The
specific heat of ice is 0.50 cal/(g x 0C); the heat of fusion for ice is 80.0 cal/g; and the specific
heat of water is 1.00 cal/(g x 0C)
b) Refer to the periodic table and write the predicted electronic configuration for each of the
following negative ions, also giving their core notation.
(i) N3(ii) I-
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4a. Draw the electron dot formula for carbonate ion, CO32-. How many pairs of nonbonding
electrons are in one molecule of CO32-
b. Given the electronegativity of the elements below, indicate which of the following are
nonpolar covalent bonds: i) Cl-Cl ii) Cl-N
iii) N-H
iv) H-P
Cl = 3.0 N= 3.0 H= 2.1 P= 2.1
5a. What is the mass of mercury that can be prepared from 1.25g of cobalt metal? Given:
Co(s) + HgCl2(aq)→ CoCl3(aq) + Hg(l)
b. Verify the conservation of mass law using the molar masses of reactants and products for
each substance in the following balanced equation:
2KNO3(s) → 2KNO2(s) + O2(g)
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6a. Dioxane is a common solvent for plastics. If the molar mass is 88g/mol and the percentage
composition is 54.5% C, 9.15% H, and 36.3% O, what is the molecular formula of dioxane?
b. Benzoyl peroxide is the active ingredient in a popular acne cream. Calculate the percentage
composition of benzoyl peroxide, C7H6O3.
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